Near-infrared absorbing glass and near-infrared cut filter

ABSTRACT

The near-infrared absorbing glass, which contains at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, and Y ions, contains P ions, Li ions, and Cu ions as essential cations, and contains at least O ions as anions, wherein a ratio (O ion/P ion) of a content of O ions relative to a content of P ions is 3.15 or less; in a glass composition indicated by anion %, a content of O ions is 90.0 anion % or more; and in an oxide-based glass composition on a molar basis, a total content of oxides of the main cations is 90.0% or more, and a total content (MgO+Al 2 O 3 ) of MgO and Al 2 O 3  is 8.0% or less.

TECHNICAL FIELD

The present invention relates to a near-infrared absorbing glass and a near-infrared cut filter

BACKGROUND ART

In recent years, image data obtained from compact cameras such as smartphones is not only digitized, but images are reconfigured by subjecting such image data to a variety of computational processes. For example, it is now common practice to extract a specific object and adjust the color and contrast of an image. During this process, if color data that was not originally present is inputted into an image element as a result of reflection of light in an optical element, this data must be removed, which is not desirable.

Near-infrared cut filters have the function of cutting out unnecessary near-infrared light (which has a wavelength of 700 to 1200 nm) in the sensitive wavelength region of an image element. A near-infrared cut filter is generally provided immediately in front of an image element.

Filters which comprise a near-infrared absorbing glass as a base material and which are polished on a flat plate are widely used as near-infrared cut filters.

Near-infrared absorbing glasses generally contain Cu ions. FIG. 1 shows an example of spectral transmission properties of a near-infrared absorbing glass. However, FIG. 1 in no way limits the present invention. Light absorption characteristics at wavelengths in the vicinity of 700 to 1200 nm are exhibited by Cu ions (Cu²⁺) in the glass. A glass that contains both Cu ions and P ions can exhibit near-infrared absorption characteristics, which are inherent in Cu ions (Cu²⁺), across a broad wavelength range, and is therefore useful as a glass for a near-infrared cut filter (for example, see PTL 1).

CITATION LIST Patent Literature

[PTL 1] Japanese Patent Application Publication No. 2014-12630

Beyond a wavelength of 600 nm in the transmittance curve in FIG. 1 , the wavelength at which the transmittance becomes 50% is known as the “half value”, and is a primary standard for the near-infrared cut filter. The half value varies according to filter specifications, but is often set to fall within the wavelength range of 600 nm to 650 nm. Ordinary methods for setting the half value to be a prescribed value include adjusting the thickness of a glass base material or the concentration of Cu ions (Cu²⁺) in a glass, in accordance with the Beer-Lambert law.

SUMMARY OF INVENTION Technical Problem

It is required for near-infrared cut filters to exhibit excellent capacity for cutting near-infrared rays (that is, need to have low transmittance of near-infrared light while having a prescribed half value), and is also required to exhibit high transmittance of light in the visible region (the violet region to the red region).

In recent years, image element modules fitted to smartphones and the like have needed to be smaller in size and higher in performance, and the thickness of near-infrared cut filters has needed to be reduced. As a result, the thickness of near-infrared absorbing glasses has been reduced from 1 mm in the past to 0.45 mm, 0.3 mm or 0.2 mm in recent years, and there have been demands for further reductions in thickness to the 0.1 mm level.

Simply reducing the thickness of a near-infrared absorbing glass leads to a reduction in the optical density of CuO (number of moles×thickness), which is required for near-infrared absorption, and this causes a reduction in the efficiency of absorption of near-infrared rays. Increasing the amount of CuO has been considered as a means for solving the above situation. However, simply increasing the amount of CuO means that CuO absorbs visible light close to a wavelength of 600 nm (that is, the red region), and because transmittance on the short wavelength side also tends to decrease, it is difficult to maintain both transmittance of light in the visible region (the violet region to the red region) and absorption of near-infrared rays.

Furthermore, in order to provide a near-infrared cut filter suitable for use in high temperature high humidity environments, it is desirable to suppress a decrease in weathering resistance of a near-infrared absorbing glass in high temperature high humidity environments. According to investigations by the present inventors, however, it is not easy to suppress a decrease in weathering resistance while maintaining both transmittance of light in the visible region (the violet region to the red region) and absorption of near-infrared rays.

With these circumstances in mind, the object of one aspect of the present invention is to provide a near-infrared absorbing glass which exhibits excellent transmittance of light in the visible region (the violet region to the red region) and near-infrared cutting performance even if the thickness of the glass is reduced and which can suppress a decrease in weathering resistance, and also to provide a near-infrared cut filter comprised of this near-infrared absorbing glass.

Solution to Problem

One aspect of the present invention relates to:

-   -   a near-infrared absorbing glass (hereinafter also referred to as         “Glass 1”) which contains at least four kinds of main cations         selected from the group consisting of P ions, Li ions, Cu ions,         Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na         ions, La ions, Gd ions, and Y ions,     -   contains P ions, Li ions, and Cu ions as essential cations,     -   and contains at least O ions as anions, wherein:     -   the ratio of the content of O ions relative to the content of P         ions (O ion/P ion) is 3.15 or less;     -   in a glass composition indicated by anion %, the content of O         ions is 90.0 anion % or more; and     -   in an oxide-based glass composition on a molar basis,     -   the total content of oxides of the main cations is 90.0% or         more,     -   the total content of MgO and Al₂O₃(MgO+Al₂O₃) is 8.0% or less,     -   the ratio of the total content of Na₂O, K₂O, and ZnO relative to         the content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less,     -   the total content of B₂O₃ and SiO₂ (B₂O₃+SiO₂) is 3.0% or less,         and     -   the content of CuO is α₁% or more,     -   where α₁ is a value calculated by Equation 1 below,

α₁=70400×exp(−2.855×R)  (Equation 1)

-   -   and in Equation 1 above,     -   R is the ratio (O ion/P ion).

Another aspect of the present invention relates to:

-   -   a near-infrared absorbing glass (hereinafter also referred to as         “Glass 2”) which contains at least four kinds of main cations         selected from the group consisting of P ions, Li ions, Cu ions,         Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na         ions, La ions, Gd ions, and Y ions,     -   contains P ions, Li ions, and Cu ions as essential cations,     -   and contains at least O ions as anions, wherein:     -   the ratio of the content of O ions relative to the content of P         ions (O ion/P ion) is 3.15 or less;     -   in a glass composition indicated by anion %, the content of O         ions is 90.0 anion % or more; and     -   in an oxide-based glass composition on a molar basis,     -   the total content of oxides of the main cations is 90.0% or         more,     -   the total content of MgO and Al₂O₃(MgO+Al₂O₃) is 8.0% or less,     -   the ratio of the total content of Na₂O, K₂O, and ZnO relative to         the content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less,     -   the total content of B₂O₃ and SiO₂ (B₂O₃+SiO₂) is 3.0% or less,         and which satisfies Equation 2 below:

C−3200×exp(−2.278×R)≥0  (Equation 2)

-   -   and in Equation 2 above,     -   C is the content of CuO (units: mmol/cc) per molar volume of the         glass, and     -   R is the ratio (O ion/P ion).

Another aspect of the present invention relates to:

-   -   a near-infrared absorbing glass (hereinafter also referred to as         “Glass 3”) which contains at least four kinds of main cations         selected from the group consisting of P ions, Li ions, Cu ions,         Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na         ions, La ions, Gd ions, Y ions, B ions and Si ions,     -   contains P ions, Li ions, and Cu ions as essential cations,     -   and contains at least O ions as anions, wherein:     -   the ratio of the content of O ions relative to the content of P         ions (O ion/P ion) is 3.15 or less;     -   in a glass composition indicated by anion %, the content of O         ions is 90.0 anion % or more; and     -   in an oxide-based glass composition on a molar basis,     -   the total content of oxides of the main cations is 90.0% or         more,     -   the total content of MgO and Al₂O₃(MgO+Al₂O₃) is 8.0% or less,     -   the ratio of the total content of Na₂O, K₂O, and ZnO relative to         the content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less,     -   A, which is calculated by Equation 3 below, is 2500 or more,

A ₁={O(P)−O(others)}×Cu  (Equation 3)

-   -   and in Equation 3 above,     -   O(P) denotes the amount of oxygen that constitutes the oxide of         P ions in the oxide-based glass composition,     -   O(others) denotes the amount of oxygen determined by subtracting         the value of O(P) from the amount of oxygen that constitutes the         oxides of the main cations in the oxide-based glass composition,         and     -   Cu denotes the content of CuO on a molar basis in the         oxide-based glass composition.

Another aspect of the present invention relates to:

-   -   a near-infrared absorbing glass (hereinafter also referred to as         “Glass 4”) which contains at least four kinds of main cations         selected from the group consisting of P ions, Li ions, Cu ions,         Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na         ions, La ions, Gd ions, Y ions, B ions and Si ions,     -   contains P ions, Li ions, and Cu ions as essential cations,     -   and contains at least O ions as anions, wherein:     -   the ratio of the content of O ions relative to the content of P         ions (O ion/P ion) is 3.15 or less;     -   in a glass composition indicated by anion %, the content of O         ions is 90.0 anion % or more; and     -   in an oxide-based glass composition on a molar basis,     -   the total content of oxides of the main cations is 90.0% or         more,     -   the total content of MgO and Al₂O₃(MgO+Al₂O₃) is 8.0% or less,     -   the ratio of the total content of Na₂O, K₂O, and ZnO relative to         the content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less, A₂,         which is calculated by Equation 4 below, is 700 or more,

A ₂={O(P)−O(others)}×C  (Equation 4)

-   -   and in Equation 4 above,     -   C is the content of CuO (units: mmol/cc) per molar volume of the         glass,     -   O(P) denotes the amount of oxygen that constitutes the oxide of         P ions in the oxide-based glass composition, and     -   O(others) denotes the amount of oxygen determined by subtracting         the value of O(P) from the amount of oxygen that constitutes the         oxides of the main cations in the oxide-based glass composition.

One aspect of the present invention relates to:

-   -   a near-infrared absorbing glass (hereinafter also referred to as         “Glass 5”) which contains at least four kinds of main cations         selected from the group consisting of P ions, Li ions, Cu ions,         Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na         ions, La ions, Gd ions, and Y ions,     -   contains P ions, Li ions, and Cu ions as essential cations,     -   and contains at least O ions as anions, wherein:     -   the ratio of the content of O ions relative to the content of P         ions (O ion/P ion) is 3.15 or less;     -   in a glass composition indicated by anion %, the content of O         ions is 90.0 anion % or more; and     -   in an oxide-based glass composition on a molar basis,     -   the total content of oxides of the main cations is 90.0% or         more,     -   the total content of MgO and Al₂O₃(MgO+Al₂O₃) is 8.0% or less,     -   the ratio of the total content of Na₂O, K₂O, and ZnO relative to         the content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less,     -   the content of CuO is α₂% or more,     -   where α₂ is a value calculated by Equation 5 below

α₂=(76522)×exp(−2.855×R)  (Equation 5)

-   -   and in Equation 5 above,     -   R is the ratio (O ion/P ion).

Another aspect of the present invention relates to:

-   -   a near-infrared absorbing glass (hereinafter also referred to as         “Glass 6”) which contains at least four kinds of main cations         selected from the group consisting of P ions, Li ions, Cu ions,         Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na         ions, La ions, Gd ions, and Y ions,     -   contains P ions, Li ions, and Cu ions as essential cations,     -   and contains at least O ions as anions, wherein     -   the ratio of the content of O ions relative to the content of P         ions (O ion/P ion) is 3.15 or less;     -   in a glass composition indicated by anion %, the content of O         ions is 90.0 anion % or more; and     -   in an oxide-based glass composition on a molar basis,     -   the total content of oxides of the main cations is 90.0% or         more,     -   the total content of MgO and Al₂O₃ (MgO+Al₂O₃) is 8.0% or less,     -   the ratio of the total content of Na₂O, K₂O, and ZnO relative to         the content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less, and     -   which satisfies Equation 6 below:

C−(3478)×exp(−2.278×R)≥0  (Equation 6)

-   -   and in Equation 6 above,     -   C is the content of CuO (units: mmol/cc) per molar volume of the         glass, and     -   R is the ratio (O ion/P ion).

Effects of Invention

According to one aspect of the present invention, it is possible to provide a near-infrared absorbing glass which exhibits excellent transmittance of light in the visible region (the violet region to the red region) and near-infrared cutting performance even if the thickness of the glass is reduced and which can suppress a decrease in weathering resistance. According to a further aspect of the present invention, it is possible to provide a near-infrared cut filter comprised of the above near-infrared absorbing glass.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows an example of spectral transmission properties of a near-infrared absorbing glass.

DESCRIPTION OF EMBODIMENTS

[Near-Infrared Absorbing Glass]

Hereinafter, Glasses 1 to 6 are also collectively referred to simply as “glass” or “near-infrared absorbing glass”. Unless explicitly stated otherwise, statements relating to the composition and physical properties of glasses apply to all of Glasses 1 to 6.

In the present invention and the present description, the term “near-infrared absorbing glass” means a glass having the property of absorbing at least light in all or part of the near-infrared wavelength region (wavelengths of 700 to 1200 nm). In addition, the near-infrared absorbing glass according to one aspect of the present invention can be an oxide glass because the glass contains O ions as constituent ions. An oxide glass is a glass in which the main network-forming components of the glass are oxides. Furthermore, the near-infrared absorbing glass according to one aspect of the present invention can be a phosphate glass because the glass contains O ions (anions) and P ions (cations) as constituent ions. O ions are anions of oxygen atoms, and are commonly referred to as oxide ions.

Detailed explanations will now be given for Glasses 1 to 6.

<Glass Composition>

(Analysis Methods)

For components that constitute a glass, the content values of elements (mass percentages of elements) contained in the glass can be quantified using well-known methods, for example inductively coupled plasma-atomic emission spectrometry (ICP-AES) or inductively coupled plasma-mass spectrometry (ICP-MS).

Anion components contained in a glass can be identified and quantified using well-known analysis methods, for example ion chromatography methods or non-dispersive infrared absorption methods (ND-IR).

In the present invention and the present description, a case where a constituent component has a content of 0% or is not contained or introduced means that this constituent component is substantially not contained and that this constituent component may be contained at an unavoidable impurity level.

(Representation of Oxide-Based Glass Composition)

Based on results obtained using the analyses mentioned above, it is possible to calculate content values (units: mol %) of components in the oxide-based glass composition. Specific methods are as follows.

By dividing the content of an element i (the mass percentage P_(i) of the element), which is obtained using an analysis method mentioned above, by the atomic weight M_(i) of the element, the number of moles n_(i) (=P_(i)/M_(i)) of the element is determined.

In a case where the above element i is a cation component A_(i), the thus obtained number of moles n_(i) of the element is replaced by the number of moles n′_(i) of the corresponding oxide. Specifically, if the compositional formula of the oxide of the cation component A_(i) corresponding to the element i is represented by A_(i)xOy, then n′_(i)=n_(i)/x.

In a case where the above element i is an anion component B_(i) other than an O ion, the number of moles n_(i) of the corresponding element is denoted by m_(i) hereinafter.

The content PA_(i) (mol %) of the oxide A_(i)xOy of the cation component A_(i) in the oxide-based glass composition is represented by:

PA_(i) =n′ _(i)/(Σn′ _(i) +Σm _(i))×100

Content values in the oxide-based glass composition can also be referred to as oxide-based proportions.

In the oxide-based glass composition, the oxide-based proportion PBi (mol %) of an anion component B_(i) other than an O ion is represented by:

PB_(i) =m _(i)/(Σn′ _(i) +Σm _(i))×100

Here, Σn′_(i) is the total number of moles of oxides AixOy of cation components contained in the glass. However, depending on the number of significant figures in content values, ignoring trace components does not affect calculation results.

(Anion %)

“Anion %” is a value calculated as “(content, indicated by mol %, of anion i in question)/(total number, indicated by mol %, of anions contained in glass)×100”, and refers to the molar ratio of the amount of the anion in question relative to the total amount of anions.

Based on the explanation above of the representation of the oxide-based glass composition, the anion % of O ions can be calculated as

(ΣO_(i)−Σ(N _(k)/2)B _(k))/(ΣO_(i) −Y(N _(k)/2)B _(k) +ΣB _(k))×100

-   -   where the compositional formula of an oxide of component A_(i)         that corresponds to the element i is represented by A_(i)xOy,         the number of O contained in an oxide of a cation component         A_(i) is denoted by O_(i)=PA_(i)×y using the oxide-based         proportion PA_(i) (mol %) of the cation component A_(i), and the         valency of an anion component B_(k) is denoted by N_(k),

Here, ΣO_(i) is the total number of moles of O ions in the oxide-based glass composition, and Σ(N_(k)/2)B_(k) denotes the number of moles of O ions replaced by the anion component B_(k). The numerator of the formula, (ΣO_(i)−Σ(N_(k)/2)B_(k)), is the number of moles of O ions contained in the glass.

Meanwhile, with regard to the content of oxygen in the present invention and the present description, if anion components other than oxygen are not detected by analysis using well-known methods, all anion components (that is, 100 anion %) are taken to be O ions.

(Cation Component)

The nominal valency of each cation is used as the valency of the cation component. The nominal valency of the cation in question is the valency required in order for the oxide of the cation to be electrically neutral when the valency of the O ion that constitutes the oxide is taken to be −2, and the nominal valency can be definitively determined from the chemical formula of the oxide.

For example, in the case of a Cu ion, the valency of Cu is +2 in order for O²⁻ and Cu contained in the chemical formula of the oxide CuO to be electrically neutral. For example, in the case of a P ion, the valency of P is +2×5/2=+5 in order for O²⁻ and P contained in the chemical formula of the oxide P₂O₅ to be electrically neutral. If this is generalized, the nominal valency of the cation Ai contained in the oxide AixOy is “+2y/×”. Therefore, when the glass composition is analyzed, the valency of cations need not be analyzed.

In addition, the valency of an anion (for example, the valency of an O ion is −2) is the nominal valency based on the understanding that an O ion receives 2 electrons to attain a closed shell structure. Therefore, when the glass composition is analyzed, the valency of anions need not be analyzed. In addition, some Cu²⁺ may become Cu⁺ upon melting, but because the amount thereof is generally small, the valency of all the Cu can be taken to be +2.

(Anion Component)

The above glass contains at least O ions as anions, and the content thereof is 90.0 anion % or more in the glass composition indicated by anion %. The present inventors considered that if the O/P ratio is lowered in a glass containing mainly O ions as anions as described above, absorption by CuO in the red region can be shifted to the long wavelength side, and it is therefore possible to increase the content of CuO and improve near-infrared cutting performance without lowering the transmittance of light in the red region. The content of O ions in the glass composition, if expressed in terms of anion %, is 90.0% or more, preferably 95.0% or more, more preferably 98.0% or more, and further preferably 99.0% or more. A high proportion of O ions in the anion component is also preferable from the perspective of suppressing volatilization when the glass melts. Suppressing volatilization when the glass melts is preferable from the perspective of suppressing the occurrence of striation. It is particularly preferable for the content of O ions to be 100% from the perspectives of suppressing volatilization when the glass melts, increasing productivity and suppressing the generation of harmful gases during production. The nominal valency of an O ion is −2.

The above glass can contain only 0 ions as anions in one embodiment, and can contain O ions and one or more other types of anion in another embodiment. Examples of other anions include F ions, Cl ions, Br ions and I ions. The nominal valency of F ions, Cl ions, Br ions and I ions is −1.

From the perspectives of improving the uniformity and strength of the glass, the content of F ions in the glass composition, if expressed in terms of anion %, is preferably 15.0 anion % or less, more preferably 10.0 anion % or less, further preferably 5.0 anion % or less, yet more preferably 2.0 anion % or less, and further preferably 1.0 anion % or less. It is particularly preferable for the glass to contain no F ions from the perspectives of suppressing volatilization when the glass melts, increasing productivity and suppressing the generation of harmful gases during production.

(O/P Ratio)

The molar ratio of the content of cations and the content of anions is the ratio of the content (expressed in mol %) of components in question, where the total amount of all cation components and all anion components is taken to be 100 mol %. Therefore, the ratio of the content of O ions relative to the content of P ions (O ions/P ions) is the ratio of the content of O ions (expressed in mol %) relative to the content of P ions (expressed in mol %), where the total amount of all cation components and all anion components is taken to be 100 mol %.

O/P Ratio Calculation Method 1

With regard to the O/P ratio (also denoted by R), the O/P ratio based on the explanation above of the representation of oxide-based glass composition can be determined from:

R1=ΣO_(i)−Σ(N _(k)/2)B _(k)  Equation D1:

R2=proportion (mol %) based on oxide of P ions (that is, P₂O₅)×2  Equation D2:

-   -   where the compositional formula of an oxide of component A that         corresponds to the element i is represented by AixOy, the number         of O contained in an oxide of a cation component Ai is denoted         by O_(i)=PA_(i)xy using the oxide-based proportion PAi (mol %)         of the cation component Ai, and the valency of an anion         component B_(k) is denoted by N_(k),     -   and the O/P ratio (R) can be determined from:

R=R1/R2  Equation D3:

For example, in an explanation using Comparative Example A below as an example, content values, if expressed in mol %, in the oxide-based glass composition of Comparative Example A are P₂O₅=53.59, Li₂O=19.30 and CuO=27.11. The number of O in these molecular formulae are 5 in P₂O₅, 1 in Li₂O and 1 in CuO. The number of moles of O in these molecular formulae are 267.95 in P₂O₅, 19.30 in Li₂O and 27.11 in CuO.

The O/P ratio in the glass in this example can be determined in the following way.

The number N_(S) of O ions is determined in the molecular formula of the glass: 53.59P₂O₅-19.30Li₂O-27.11 CuO. The molecular formula of the glass is the compositional formula of the glass expressed in such a way that the total amount of molecules contained in the glass is 100.

That is, using the numbers of O ions contained in the molecular formula MxOy of the oxides (5 in P₂O₅, 1 in Li₂O, and 1 in CuO),

-   -   the value of N_(S) is calculated as:

N _(S)=53.59×5+19.30×1+27.11×2=314.36

In the glass in the example mentioned above, because the amount of O ions replaced by other anions in the molecular formula of the glass is O, by dividing this N_(S) value (314.36) by the number of moles of P contained in P₂O₅ (53.59)×2, the O/P ratio can be determined as 314.36/(53.59×2)=2.93.

O/P Ratio Calculation Method 2

In a case where one or more types of anion component other than oxygen are detected in analysis using a well-known method, the content of oxygen can be the content (units: anion %) calculated using a method shown in section (3) below from (1) the content of cations based on the valency of cation components contained in the glass and the molar percentages of elements, and (2) the content of anions based on the valency of anion components other than oxygen and the molar percentages of elements.

That is, based on results of identification and quantification analysis using a well-known method,

-   -   (1) the total U of “the content of cations based on the number         of oxygens per cation (y/x)×molar percentages of elements, where         the number of oxygens is denoted by y and the number of cations         is denoted by x in an oxide MxOy” is calculated for cation         components contained in the glass,     -   (2) the total V of “content of anions based on molar percentages         of elements×number of substituted oxygens (z/2) per anion” is         calculated for anion components other than oxygen based on         results of identification and quantification analysis using         well-known methods and the valency z of anions, and     -   (3) the value of U-V can also be used as the content of O ions         relative to the content of the P ions.

Calculation example 1 and calculation example 2 below are given as examples of calculation method 2.

Calculation example 1: when the molar percentages of elements of P ions, Li ions and Cu ions were quantitatively determined as 22.0, 8.0 and 5.5 (content values expressed as molar percentages of elements), the values of y/x in the corresponding oxides (P₂O₅, Li₂O and CuO) are 2.5, 0.5 and 1.0 respectively,

-   -   the value of U is 22×2.5+8×0.5+5.5×1.0=64.5, and     -   the value of V is 0.

Therefore, the molar percentage of O ions based on the molar percentages of these elements is 64.5 (content expressed as molar percentage of element).

From the ratio of the value for O ions determined in this way and the analyzed molar percentage of P ions, the O/P ratio can be determined as 64.5/22=2.93 . . . .

Calculation example 2: when the molar percentages of elements of P ions, Li ions and Cu ions were quantitatively determined as 22.0, 8.0 and 5.5 (content values expressed as molar percentages of elements) and the molar percentage of the element in F ions was quantitatively determined as 4.0 (a content value expressed as the molar percentage of the element), the values of y/x in the corresponding oxides (P₂O₅, Li₂O and CuO) are 2.5, 0.5 and 1.0 respectively, and because the valency of F is −1,

-   -   the value of U is 22×2.5+8×0.5+5.5×1.0=64.5, and     -   the value of V is 4×½=2.

Therefore, the molar percentage of O ions based on the molar percentages of these elements is 62.5 (content expressed as molar percentage of element).

From the ratio of the value for O ions determined in this way and the analyzed molar percentage of P ions, the O/P ratio can be determined as 62.5/22=2.84 . . . .

In Glasses 1 to 6, the ratio (O/P ratio) of the content of O ions relative to the content of P ions is 3.15 or less from the perspective of achieving both improved transmittance of light in the visible region and improved near-infrared cutting performance and also from the perspective of improving the thermal stability of the glass.

In Glasses 1 to 6, the O/P ratio is preferably 3.14 or less, and is more preferably 3.13 or less, 3.12 or less, 3.11 or less, 3.10 or less, 3.09 or less, 3.08 or less, 3.07 or less, 3.06 or less, 3.05 or less, 3.04 or less, 3.03 or less, 3.02 or less, 3.01 or less, or 3.00 or less in that order.

On the other hand, the O/P ratio in Glasses 1 to 6 is preferably high from the perspectives of improving weathering resistance and/or suppressing a decrease in meltability. From this perspective, the O/P ratio in Glasses 1 to 6 is preferably 2.50 or more, and is more preferably 2.60 or more, 2.65 or more, 2.70 or more, 2.73 or more, 2.75 or more, 2.77 or more, 2.80 or more, 2.81 or more, 2.82 or more, 2.83, 2.84 or more, or more, 2.85 or more, 2.86 or more, 2.87 or more, 2.88 or more, 2.89 or more, or 2.90 or more in that order.

(Cation Component)

Glasses 1 to 6 contain at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, and Y ions, and contain P ions, Li ions and Cu ions as essential cations. In the oxide-based glass composition (on a molar basis) of Glasses 1 to 6, the total content of oxides of the main cations is 90.0 mol % or more.

In Glasses 1 to 6, the total content of oxides of the main cations being 90.0% or more can contribute to an improvement in thermal stability of the glasses and/or an improvement in the optical uniformity of the glass by suppressing striation, volatilization, and the like. From the above perspective, the total content of oxides of the main cations in Glasses 1 to 6 is preferably 92.0% or more, is more preferably 93.0% or more, 95.1% or more, 96.1% or more, 97.1% or more, 98.1 or more, 98.6% or more, 99.1% or more, or 99.6% or more in that order, and can be 100%. In one embodiment, the total content of oxides of the main cations in Glasses 1 to 6 can be 100% or less, 99.5% or less, 99% or less, 98.5% or less, 98.0% or less, or 97.5% or less.

An explanation will now be given of the content of a cation component as the content (on a molar basis) in the oxide-based glass composition.

Because CuO is an essential component for imparting near-infrared cutting performance to the glass, Glasses 1 to 6 contain Cu ions as essential cations.

In Glass 1, the content of CuO is a1% or more. α₁ can be calculated from Equation 1 below.

α₁=70400×exp(−2.855×R)  (Equation 1)

In Equation 1, R is the O/P ratio.

In Glass 2, the lower limit for the content of CuO is defined by Equation 2 below from the content of CuO per molar volume of the glass.

C−3200×exp(−2.278×R)≥0  (Equation 2)

In Equation 2, C is the content of CuO (units: mmol/cc) per molar volume of the glass, and R is the O/P ratio.

In Equation 2, the value of C is determined using the following method.

C can be calculated as:

C=mol % of CuO/(M/D)×1000 (units: mmol/cc)

-   -   by measuring the specific gravity D (g/cc) of the glass,         determining the mass per mole of the glass composition, that is,         the molar molecular weight M (g/mol), on the basis of the glass         composition obtained through analysis in the manner described         above, and determining the molar volume M/D (units: cc/mol) of         the glass.

The molar molecular weight M mentioned above can be calculated as

M={Σ(PA_(i)×MA_(i))+Σ(PB_(k)×MB_(k))−Σ(N _(k)/2)Mo}/ΣPA_(i)

-   -   where the formula weight of an oxide corresponding to the cation         component Ai mentioned above is denoted by MA_(i), the atomic         weight of the anion component B_(k) is denoted by MB_(k), and         the atomic weight of oxygen is denoted by Mo, based on the         explanation above of the representation of the oxide-based glass         composition

For example, if the glass composition is constituted from s mol % of a component A₂O on an oxide basis, t mol % of a component BO on an oxide basis and u mol % of a component F, the value of s+t+u is 100(%), the formula weight of the component A₂O is M_(A) (g/mol), the formula weight of the component BO is M_(B) (g/mol), the atomic weight of F is M_(F) (g/mol), and the atomic weight of oxygen is M_(O) (g/mol), then

M=(s×M _(A) +t×M _(B) +u×M _(F) −u/2×M _(O))/(s+t)

For example, the molar molecular weight M of Comparative Example A below (in which content values expressed as molar percentages in the oxide-based glass composition are P₂O₅=53.59, Li₂O=19.30 and CuO=27.11) can be calculated as: M=(53.59×141.94+19.30×29.88+27·11×79.55)/(53.59+19.30+27.11)=103.40 (g/mol) using:

Formula weight of P₂O₅: 141.94 (g/mol)

Formula weight of Li₂O: 29.88 (g/mol)

Formula weight of CuO: 79.55 (g/mol)

As a result of extensive research by the present inventors, it was newly found that by lowering the O/P ratio in a glass containing mainly O ions as anions, absorption by CuO in the red region can be shifted to the long wavelength side, thereby suppressing a reduction in the transmittance of light in the red region and enabling the content of CuO to be increased. The present inventors also newly found that there is a strong correlation between the O/P ratio and the content of CuO, which is required in order to achieve a prescribed half value at a prescribed thickness, and the lower limit for the content of CuO (α₁, α₂) is specified by Equation 1 for Glass 1, in which the O/P ratio falls within the range mentioned above, and by Equation 5 for Glass 5. In addition, for a glass in which the O/P ratio falls within the range mentioned above, the content of CuO per molar volume of the glass is specified by Equation 2, and for Glass 6, the content of CuO per molar volume of the glass is specified by Equation 6.

In Glass 3, the content of CuO is defined on the basis of A₁, which is calculated from Equation 3 below, and the value of A₁ is 2500 or more.

A ₁={O(P)−O(others)}×Cu  (Equation 3)

In equation 3, O(P) denotes the amount of oxygen that constitutes the oxide of P ions in the oxide-based glass composition, O(others) denotes the amount of oxygen determined by subtracting the value of O(P) from the amount of oxygen that constitutes the oxides of the main cations already mentioned in Glass 3 in the oxide-based glass composition, and Cu denotes the content of CuO on a molar basis in the oxide-based glass composition.

In Equation 3, “O(P)” is calculated in the following way.

If the content (on a molar basis) of P₂O₅ in the oxide-based glass composition is denoted by M mol %, the value of O(P) is calculated as “O(P)=M×5” using the number of oxygens (5) included in the chemical formula P₂O₅.

Similarly, for main cations other than P ions, the amount of oxygen that constitutes the oxides of these cations is calculated using the content values of the oxides (on a molar basis) in the oxide-based glass composition and the number of oxygens contained in the oxides formed in a state where the cations have nominal valencies.

The value of “O(others)” is calculated as a value obtained by subtracting the value of O(P) from the total amount of oxygen calculated for the oxides of the main cations.

If the content of CuO (on a molar basis) in the oxide-based glass composition is denoted by N mol %, the value of “A” is calculated as A₁={O(P)−O(others)}×N. As mentioned above, the present inventors newly found that by lowering the O/P ratio in a glass containing mainly O ions as anions, absorption by CuO in the red region can be shifted to the long wavelength side, thereby suppressing a reduction in the transmittance of light in the red region and enabling the content of CuO to be increased. It was also newly found that by using a chemical species which has a smaller ionic radius and a lower valency as a chemical species other than P—O that coordinates to CuO, it is possible to increase transmittance in the visible light region (the violet region to the red region) as a result of features 1) and 2) below. In view of these findings, the content of CuO in Glass 3 is defined on the basis of A, which is calculated from Equation 3.

1) By shifting absorption derived from Cu²⁺ to the long wavelength side, it is possible to increase the transmittance of light in the red region.

2) By enabling the glass to be in a liquid phase state at a low temperature, it is possible to suppress the generation of Cu₊, which exhibits absorption of light in the violet region close to a wavelength of 400 nm.

For Glass 3, the value of A₁ is 2500 or more, is preferably 2800 or more, and is more preferably 2900 or more, 3000 or more, 3100 or more, 3200 or more, 3300 or more, 3400 or more, 3500 or more, 3600 or more, 3700 or more, 3800 or more, 3900 or more, 4000 or more, 4100 or more, 4200 or more, 4300 or more, 4400 or more, 4500 or more, 4600 or more, 4700 or more, 4800 or more, 4900 or more, 5000 or more, 5100 or more, 5200 or more, 5300 or more, 5400 or more, 5500 or more, 5600 or more, 5700 or more, 5800 or more, 5900 or more, 6000 or more, 6100 or more, 6200 or more, 6300 or more, 6400 or more, or 6500 or more in that order from the perspective of achieving both improved transmittance of light in the visible region and improved near-infrared cutting performance. On the other hand, from the perspectives of suppressing a decrease in the thermal stability of the glass due to a high content of Cu and O, suppressing a decrease in transmittance at a desired half value wavelength and/or suppressing a decrease in thermal stability or weathering resistance of the glass due to an excessively low O(others) value, the value of A is preferably 20000 or less, and is more preferably 19000 or less, 18000 or less, 17000 or less, 16000 or less, 150000 or less, 14000 or less, 13000 or less, 12000 or less, 11000 or less, 10000 or less, 9000 or less, or 8000 or less. In order to achieve a desired half value at a lower thickness, it tends to be desirable for this numerical value to be high.

In Glass 4, the content of CuO is defined on the basis of A₂, which is calculated from Equation 4 below, and the value of A₂ is 700 or more.

A ₂={O(P)−O(others)}×C  (Equation 4)

In Equation 4, C is the content of CuO (units: mmol/cc) per molar volume of the glass. O(P) denotes the amount of oxygen that constitutes the oxide of P ions in the oxide-based glass composition, and O(others) denotes the amount of oxygen determined by subtracting the value of O(P) from the amount of oxygen that constitutes the oxides of the above main cations in the oxide-based glass composition.

For Glass 4, the value of A₂ is 700 or more, is preferably 800 or more, and is more preferably 850 or more, 890 or more, 1000 or more, 1100 or more, 1200 or more, 1300 or more, 1400 or more, 1500 or more, 1600 or more, 1700 or more, or 1800 or more in that order from the perspective of achieving both improved transmittance of light in the visible region and improved near-infrared cutting performance. On the other hand, from the perspectives of suppressing a decrease in the thermal stability of the glass due to a high content of Cu and O, suppressing a decrease in transmittance at a desired half value wavelength and/or suppressing a decrease in thermal stability or weathering resistance of the glass due to an excessively low O(others) value, the value of A₂ is preferably 5000 or less, and is more preferably 4000 or less, 3500 or less, 3000 or less, 2500 or less, or 2000 or less. In order to achieve a desired transmittance half value at a lower thickness, it tends to be desirable for this numerical value to be high.

In addition, in Glass 5, the content of CuO is a2% or more. α₂ can be calculated from Equation 5 below.

α₂=76522×exp(−2.855×R)  (Equation 5)

In Equation 5, R is the O/P ratio.

In addition, in Glass 6, the lower limit for the content of CuO is defined by Equation 6 below from the content of CuO per molar volume of the glass.

C−3478×exp(−2.278×R)≥0  (Equation 6)

In Equation 6, C is the content of CuO (units: mmol/cc) per molar volume of the glass, and R is the O/P ratio.

The content of CuO in the oxide-based glass composition (on a molar basis) of Glasses 1 to 6 is preferably 4.0% or more, and is more preferably 5.0% or more, 6.0% or more, 7.0% or more, 7.5% or more, 8.0% or more, 8.5% or more, 9.0% or more, 9.5% or more, 10.0% or more, 10.5% or more, 11.0% or more, 11.5% or more, 12.0% or more, 12.5% or more, 13.0% or more, 13.5% or more, 14.0% or more, 14.5% or more, 15.0% or more, 15.5% or more, 16.0% or more, 16.5% or more, 17.0% or more, 17.5% or more, 18.0% or more, 18.5% or more, 19.0% or more, 19.5% or more, or 20.0% or more in that order. From the perspectives of leaving room for introduction of glass-forming components and maintaining the thermal stability of the glass, the content of CuO is preferably 48.0% or less, and is more preferably 47.0% or less, 46.0% or less, 45.0% or less, 44.0% or less, 43.5% or less, 43.0% or less, 42.5% or less, 42.0% or less, 41.5% or less, 41.0% or less, 40.5% or less, 40.0% or less, 39.5% or less, 39.0% or less, 38.5% or less, 38.0% or less, 37.5% or less, 37.0% or less, 36.5% or less, 36.0% or less, 35.5% or less, 35.0% or less, 34.5% or less, 34.0% or less, 33.5% or less, 33.0% or less, 32.5% or less, 32.0% or less, 31.5% or less, or 31.0% or less in that order.

As a transmittance characteristic calculated at a thickness of 0.11 mm, in order for the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm, the content of CuO in the oxide-based glass composition (on a molar basis) is preferably 15.0% or more, and is more preferably 15.5% or more, 16.0% or more, 16.5% or more, 17.0% or more, 17.5% or more, 18.0% or more, 18.5% or more, 19.0% or more, 19.5% or more, or 20.0% or more in that order.

As a transmittance characteristic calculated at a thickness of 0.21 mm, in order for the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm, the content of CuO in the oxide-based glass composition (on a molar basis) is preferably 10.0% or more, and is more preferably 10.5% or more, 11.0% or more, 11.5% or more, 12.0% or more, 12.5% or more, 13.0% or more, 13.5% or more, 14.0% or more, 14.5% or more, 15.0% or more, 15.5% or more, 16.0% or more, 16.5% or more, 17.0% or more, 17.5% or more, 18.0% or more, 18.5% or more, 19.0% or more, 19.5% or more, or 20.0% or more in that order.

As a transmittance characteristic calculated at a thickness of 0.25 mm, in order for the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm, the content of CuO in the oxide-based glass composition (on a molar basis) is preferably 10.0% or more, and is more preferably 10.5% or more, 11.0% or more, 11.5% or more, 12.0% or more, 12.5% or more, 13.0% or more, 13.5% or more, 14.0% or more, 14.5% or more, 15.0% or more, 15.5% or more, 16.0% or more, 16.5% or more, 17.0% or more, 17.5% or more, 18.0% or more, 18.5% or more, 19.0% or more, 19.5% or more, or 20.0% or more in that order.

On the other hand, because the transmittance characteristic calculated at a thickness of 0.25 mm is such that the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50%, may be lower than 600 nm if the content of CuO is too high, the content of CuO is preferably 35.0% or less, and is more preferably 34.0% or less, 33.0% or less, 32.0% or less, 31.0% or less, 30.0% or less, 29.5% or less, 29.0% or less, 28.5% or less, 28.0% or less, 27.5% or less, 27.0% or less, 26.5% or less, 26.0% or less, 25.5% or less, 25.0% or less, 24.5% or less, 24.0% or less, 23.5% or less, 23.0% or less, 22.5% or less, 22.0% or less, 21.5% or less, 21.0% or less, 20.5% or less, or 20.0% or less in that order.

In order for the glass thickness at which the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm to be 0.25 mm or less, the content of CuO in the oxide-based glass composition (on a molar basis) is preferably 10.0% or more, and is more preferably 10.5% or more, 11.0% or more, 11.5% or more, 12.0% or more, 12.5% or more, 13.0% or more, 13.5% or more, 14.0% or more, 14.5% or more, 15.0% or more, 15.5% or more, 16.0% or more, 16.5% or more, 17.0% or more, 17.5% or more, 18.0% or more, 18.5% or more, 19.0% or more, 19.5% or more, or 20.0% or more in that order.

In order for the glass thickness at which the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm to be 0.25 mm or less, the content of CuO in the oxide-based glass composition (on a molar basis) is preferably 10.5% or more, and is more preferably 11.0% or more, 11.5% or more, 12.0% or more, 12.5% or more, 13.0% or more, 13.5% or more, 14.0% or more, 14.5% or more, 15.0% or more, 15.5% or more, 16.0% or more, 16.5% or more, 17.0% or more, 17.5% or more, 18.0% or more, 18.5% or more, 19.0% or more, 19.5% or more, or 20.0% or more in that order.

In Glass 2 and Glass 4, the value of C is preferably 3.0 or more, and is more preferably 3.1 or more, 3.3 or more, 3.5 or more, 3.7 or more, 3.9 or more, 4.0 or more, 4.1 or more, 4.2 or more, 4.3 or more, 4.4 or more, 4.5 or more, 4.6 or more, 4.7 or more, 4.8 or more, 4.9 or more, 5.0 or more, 5.1 or more, 5.2 or more, 5.3 or more, 5.4 or more, or 5.5 or more in that order. From the perspectives of leaving room for introduction of glass-forming components and maintaining the thermal stability of the glass, the value of C is preferably 16.0 or less, and is more preferably 15.0 or less, 14.0 or less, 13.5 or less, 13.0 or less, 12.5 or less, 12.0 or less, 11.9 or less, 11.8 or less, 11.7 or less, 11.6 or less, 11.5 or less, 11.4 or less, 11.3 or less, 11.2 or less, 11.1 or less, 11.0 or less, 10.9 or less, 10.8 or less, 10.7 or less, 10.6 or less, 10.5 or less, 10.4 or less, 10.3 or less, 10.2 or less, 10.1 or less, 10.0 or less, 9.9 or less, 9.8 or less, 9.7 or less, 9.6 or less, 9.5 or less, 9.4 or less, 9.3 or less, 9.2 or less, 9.1 or less, 9.0 or less, 8.9 or less, 8.8 or less, 8.7 or less, 8.6 or less, or 8.5 or less in that order.

In Glasses 1 to 6, the content of CuO can be a3% or more. α₃ can be calculated from Equation 7 below.

α₃=(70400×0.25/d)×exp(−2.855×R)  (Equation 7)

In Equation 7, R is the O/P ratio. The value of d can be more than 0 and not more than 0.25. For example, the value of d can be 0.25, 0.24, 0.23, 0.22, 0.21, 0.20, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, 0.11, 0.10, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, and the like. However, the value of d is not limited to these values. In order to achieve a desired transmittance half value at a lower thickness, it tends to be desirable for the value of d to be low.

For example, if d=0.11, the content of CuO can be a3% or more, and the value of a3 is calculated from the equation below.

α₃=(70400×0.25/0.11)×exp(−2.855×R)

In one embodiment, if D (mm) denotes the sheet thickness of the glass at which the external transmittance of light having a wavelength of 633 nm becomes 50%, it is possible for d=D in Equation 7 above. In this case, the value of a3 is calculated from the equation below.

α₃=(70400×0.25/D)×exp(−2.855×R)

In Glasses 1 to 6, the lower limit for the content of CuO can be defined by Equation 8 below from the content of CuO per molar volume of the glass.

C−3200×0.25/d×exp(−2.855×R)≥0  (Equation 8)

In Equation 8, the value of d can be more than 0 and not more than 0.25. For example, the value of d can be 0.25, 0.24, 0.23, 0.22, 0.21, 0.20, 0.19, 0.18, 0.17, 0.16, 0.15, 0.14, 0.13, 0.12, 0.11, 0.10, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, 0.01, and the like. However, the value of d is not limited to these values. In order to achieve a desired transmittance half value at a lower thickness, it tends to be desirable for the value of d to be low.

For example, if d=0.11, Equation 8 is the following equation.

C−3300×0.25/0.11×exp(−2.855×R)≥0

In one embodiment, if D (mm) denotes the sheet thickness of the glass at which the external transmittance of light having a wavelength of 633 nm becomes 50%, it is possible for d=D in Equation 8 above. In this case, Equation 8 is the following equation.

With regard to the content of CuO, Glasses 1 to 6 can also satisfy one or more other glass-related equations.

Glasses 1 to 6 contain P ions as essential cations. As mentioned above, a low O/P ratio is preferred from the perspective of achieving both improved transmittance of light in the visible region and improved near-infrared cutting performance. It is preferable to increase the content of P₂O₅ in order to lower the O/P ratio. From this perspective, the content of P₂O₅ in the oxide-based glass composition (on a molar basis) is preferably 33.0% or more, and is more preferably 34.0% or more, 35.0% or more, 36.0% or more, 37.0% or more, 38.0% or more, 39.0% or more, 40.0% or more, 40.5% or more, 41.0% or more, 41.5% or more, 42.0% or more, 42.5% or more, 43.0% or more, 43.5% or more, 44.0% or more, 44.5% or more, 45.0% or more, 45.5% or more, 46.0% or more, 46.5% or more, 47.0% or more, 47.5% or more, 48.0% or more, 48.5% or more, 49.0% or more, 49.5% or more, or 50.0% or more in that order. Because P₂O₅ itself does not exhibit near-infrared absorption capacity, the content of P₂O₅ is preferably 72.0% or less, and is more preferably 71.0% or less, 70.0% or less, 69.5% or less, 69.0% or less, 68.5% or less, 68.0% or less, 67.5% or less, 67.0% or less, 66.5% or less, 66.0% or less, 65.5% or less, 65.0% or less, 64.5% or less, 64.0% or less, 63.5% or less, 63.0% or less, 62.5% or less, 62.0% or less, 61.5% or less, 61.0% or less, 60.5% or less, or 60.0% or less in that order from the perspective of increasing the content of CuO, which does exhibit near-infrared absorption capacity. In addition, it is preferable for the content of P₂O₅ to be not higher than the value mentioned above from the perspectives of further suppressing a decrease in weathering resistance and/or suppressing a decrease in meltability.

In the glasses mentioned above, it is preferable for the oxide-based glass composition to be constituted mainly from P₂O₅, Li₂O and CuO in order to achieve the desired transmission characteristics. From this perspective, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) is preferably 50.0% or more, and is more preferably 55.0% or more, 60.0% or more, 65.0% or more, 70.0% or more, 75.0% or more, 80.0% or more, 83.0% or more, 86.0% or more, 88.0% or more, or 90.0% or more in that order. The glasses mentioned above contain P ions, Li ions and Cu ions as essential cations, and also contain one or more types of cation selected from among the main cation group in order for the glasses to exhibit thermal stability and/or chemical durability. Therefore, the total content (P₂O₅+Li₂O+CuO) is less than 100%, is preferably 9.9% or less, and is more preferably 99.8% or less, 99.7% or less, 99.6% or less, 99.5% or less, 99.4% or less, 99.2% or less, 99.0% or less, 98.0% or less, 97.0% or less, 96.0% or less, 95.0% or less, 94.0% or less, 93.0% or less, 92.0% or less, 91.0% or less, 90.0% or less, 89.0% or less, 88.0% or less, 87.0% or less, 86.0% or less, or 85.0% or less in that order.

As a transmittance characteristic calculated at a thickness of 0.11 mm, in order for the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm in one embodiment, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 84.0% or more, and is more preferably 85.0% or more, 86.0% or more, 87.0% or more, 88.0% or more, 89.0% or more, or 90.0% or more in that order.

As a transmittance characteristic calculated at a thickness of 0.21 mm, in order for the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 80.0% or more, and is more preferably 81.0% or more, 82.0% or more, 83.0% or more, 84.0% or more, 85.0% or more, 86.0% or more, 87.0% or more, 88.0% or more, 89.0% or more, or 90.0% or more in that order.

As a transmittance characteristic calculated at a thickness of 0.25 mm, in order for the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 75.0% or more, and is more preferably 76.0% or more, 77.0% or more, 78.0% or more, 79.0% or more, 80.0% or more, 81.0% or more, 82.0% or more, 83.0% or more, 84.0% or more, 85.0% or more, 86.0% or more, 87.0% or more, 88.0% or more, 89.0% or more, or 90.0% or more in that order.

In order for the glass thickness at which the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm to be 0.25 mm or less, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 80.0% or more, and is more preferably 81.0% or more, 82.0% or more, 83.0% or more, 84.0% or more, 85.0% or more, 86.0% or more, 87.0% or more, 88.0% or more, 89.0% or more, or 90.0% or more in that order.

In order for the glass thickness at which the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm to be 0.25 mm or less, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 81.0% or more, and is more preferably 82.0% or more, 83.0% or more, 84.0% or more, 85.0% or more, 86.0% or more, 87.0% or more, 88.0% or more, 89.0% or more, or 90.0% or more in that order.

Glasses of Examples 1 to 60 below can be given as examples of glasses corresponding to the above embodiment.

On the other hand, as another embodiment, for a glass in which the molar ratio ((MgO+CaO+SrO+BaO+ZnO)/(Li₂O+Na₂O+K₂O)) of the total content of MgO, CaO, SrO, BaO and ZnO (MgO+CaO+SrO+BaO+ZnO) relative to the total content of Li₂O, Na₂O and K₂O (Li₂O+Na₂O+K₂O) is 2.0 or more, in order for the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm as a transmittance characteristic calculated at a thickness of 0.11 mm, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 65.0% or more, and is more preferably 66.0% or more, 67.0% or more, 68.0% or more, 69.0% or more, or 70.0% or more in that order.

As a transmittance characteristic calculated at a thickness of 0.21 mm, in order for the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm in another embodiment mentioned above, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 60.0% or more, and is more preferably 61.0% or more, 62.0% or more, 63.0% or more, 64.0% or more, or 65.0% or more in that order.

As a transmittance characteristic calculated at a thickness of 0.25 mm, in order for the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50%, to fall within the range 600 nm to 650 nm in another embodiment mentioned above, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 55.0% or more, and is more preferably 56.0% or more, 57.0% or more, 58.0% or more, 59.0% or more, or 60.0% or more in that order.

In order for the glass thickness at which the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm to be 0.25 mm or less in another embodiment mentioned above, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 60.0% or more, and is more preferably 61.0% or more, 62.0% or more, 63.0% or more, 64.0% or more, or 65.0% or more in that order.

In order for the glass thickness at which the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm to be 0.25 mm or less in another embodiment mentioned above, the total content of P₂O₅, Li₂O and CuO (P₂O₅+Li₂O+CuO) in the oxide-based glass composition (on a molar basis) is preferably 61.0% or more, and is more preferably 62.0% or more, 63.0% or more, 64.0% or more, 65.0% or more, or 66.0% or more in that order.

Glasses of Examples 61 to 66 below can be given as examples of glasses corresponding to another embodiment mentioned above.

For Glasses 3 and 4, the main cation group mentioned above includes B ions and Si ions. For Glasses 1, 2, 5 and 6, on the other hand, the main cation group mentioned above does not include B ions or Si ions, which tend to increase the melting temperature. In one embodiment, Glasses 1 to 6 can be glasses which contain B ions and/or Si ions, which shift the half value to the short wavelength side, from the perspectives of increasing the near-infrared cutting performance of the glass and improving the transmittance of light in the visible region, and can be glasses that contain no B ions and no Si ions in another embodiment.

From the perspective of improving the transmittance of light in the visible region, the total content of B₂O₃ and SiO₂ (B₂O₃+SiO₂) in the oxide-based glass composition (on a molar basis) of Glass 1 and Glass 2 is 3.0% or less, is preferably 2.5% or less, and is more preferably 2.0% or less, 1.5% or less, 1.0% or less, or 0.5% or less in that order.

From the perspective of further improving the transmittance of light in the visible region, the total content of B₂O₃ and SiO₂ (B₂O₃+SiO₂) in the oxide-based glass composition (on a molar basis) of Glasses 3 to 6 is preferably 3.0% or less, and is more preferably 2.5% or less, 2.0% or less, 1.5% or less, 1.0% or less, or 0.5% or less in that order.

In Glasses 1 to 6, the total content of B₂O₃ and SiO₂ (B₂O₃+SiO₂) can be 0%, 0% or more, or more than 0%.

From the perspective of greatly improving the transmittance of light in the visible region, the content of B₂O₃ in Glasses 1 to 6 is preferably 3.0% or less, and is more preferably 2.5% or less, 2.0% or less, 1.5% or less, 1.0% or less, or 0.5% or less in that order. The content of B₂O₃ can be 0%.

For Glasses 1 to 6, on the other hand, in a case where a quartz crucible is used for crudely melting the glass in order to facilitate homogenization of the glass, the content of SiO₂ is preferably more than 0%, and is more preferably 0.01% or more, 0.02% or more, 0.03% or more, 0.04% or more, 0.05% or more, 0.1% or more, 0.2% or more or 0.3% or more in that order. However, excessive introduction of SiO₂ into the glass tends to lower the optical uniformity of the glass. From this perspective, the content of SiO₂ in Glasses 1 to 6 is preferably 2.0% or less, and is more preferably 1.4% or less, 0.9% or less, 0.8% or less, 0.6% or less, or 0.4% or less in that order.

Glasses 1 to 6 contain Li ions as essential cations. Compared to a variety of glass components, Li₂O has a high ability to maintain absorption by CuO in the long wavelength region, and has small adverse effect on weathering resistance. From this perspective, the content of Li₂O is preferably 0.1% or more, and is more preferably 0.5% or more, 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, 4.0% or more, 4.5% or more, 5.0% or more, 5.5% or more, 6.0% or more, 6.5% or more, 7.0% or more, 7.5% or more, or 8.0% or more in that order. On the other hand, from the perspective of ensuring thermal stability of the glass and/or the perspective of further suppressing a decrease in weathering resistance, the content of Li₂O is preferably 35.0% or less, and is more preferably 34.0% or less, 33.0% or less, 32.0% or less, 31.0% or less, 30.0% or less, 29.5% or less, 29.0% or less, 28.5% or less, 28.0% or less, 27.5% or less, 27.0% or less, 26.5% or less, 26.0% or less, 25.5% or less, 25.0% or less, 24.5% or less, 24.0% or less, 23.5% or less, 23.0% or less, 22.5% or less, 22.0% or less, 21.5% or less, 21.0% or less, 20.5% or less, or 20.0% or less in that order.

From the perspectives of improving meltability and improving the transmittance of light in the visible region, the total content of MgO and Al₂O₃(MgO+Al₂O₃) in Glasses 1 to 6 is 8.0% or less, is preferably 7.5% or less, is more preferably 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, 2.5% or less, 2.0% or less, 1.8% or less, 1.6% or less, 1.5% or less or 1.4% or less in that order, and can be 0%. On the other hand, from the perspectives of increasing the weathering resistance of the glass and improving the mechanical strength of the glass, the total content of MgO and Al₂O₃(MgO+Al₂O₃) can be more than 0%, is preferably 0.1% or more, and is more preferably 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.6% or more, 0.7% or more, 0.8% or more, 0.9% or more, 1.0% or more, 1.1% or more, or 1.3% or more in that order.

Al₂O₃ is a component that can contribute to an increase in weathering resistance in particular. The content of Al₂O₃ can be 0%, 0% or more, or more than 0%, and from the perspective of increasing the weathering resistance of the glass, is preferably 0.1% or more, and is more preferably 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.6% or more, 0.7% or more, 0.9% or more, 1.1% or more, 1.3% or more, or 1.5% or more in that order. On the other hand, from the perspective of further suppressing a decrease in the transmittance of light in the visible region, the content of Al₂O₃ is preferably 8.0% or less, and is more preferably 7.5% or less, 7.0% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, or 2.5% or less in that order. In one embodiment, from the perspectives of prioritizing improving near-infrared absorption properties rather than maintaining the weather resistance of the glass, increasing the transmittance of light in the visible region by suppressing a short-wavelength shift of CuO absorption, and improving near-infrared absorption properties, the content of Al₂O₃ is preferably less than 2.0%, and is more preferably 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, 1.0% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, or 0.5% or less in that order.

MgO is a component that can be added, as appropriate, in order to adjust the thermal stability of the glass, but MgO shifts absorption by CuO to the short wavelength side, and it therefore tends to be difficult to increase the content of CuO. In addition, as the content of MgO increases, the meltability of the glass tends to decrease. From these perspectives, the content of MgO is preferably 9.0% or less, and is more preferably 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, or 2.0% or less in that order. The content of MgO can be 0%. In one embodiment, the content of MgO can be more than 0%, is preferably 0.5% or more, and is more preferably 1.0% or more from the perspective of improving the mechanical strength of the glass.

La₂O₃ is a component that can contribute to an increase in weathering resistance without sacrificing the near-infrared absorption characteristics of the glass. The content of La₂O₃ is preferably 0.10% or more, and is more preferably 0.15% or more, 0.18% or more, or 0.21% or more in that order. On the other hand, from the perspective of further suppressing a decrease in the transmittance of light in the visible region, the content of La₂O₃ is preferably 8.0% or less, and is more preferably 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, 2.5% or less, 2.0% or less, 1.5% or less, or 1.0% or less in that order.

Y₂O₃ is also a component that can contribute to an increase in weathering resistance without sacrificing the near-infrared absorption characteristics of the glass. The content of Y₂O₃ is preferably 0.10% or more, and is more preferably 0.15% or more, 0.20% or more, 0.25% or more, 0.30% or more, 0.35% or more, 0.40% or more, 0.45% or more, or 0.50% or more in that order. On the other hand, from the perspective of further suppressing a decrease in the transmittance of light in the visible region, the content of Y₂O₃ is preferably 8.0% or less, and is more preferably 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, 2.5% or less, 2.0% or less, 1.5% or less, or 1.0% or less in that order. It is possible to introduce Y₂O₃ from the perspective of increasing the molar volume of the glass without increasing the specific gravity of the glass.

Gd₂O₃ is also a component that can contribute to an increase in weathering resistance. The content of Gd₂O₃ is preferably 0.10% or more, and is more preferably 0.15% or more, 0.18% or more, or 0.21% or more in that order. On the other hand, from the perspective of further suppressing a decrease in the transmittance of light in the visible region, the content of Gd₂O₃ is preferably 8.0% or less, and is more preferably 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, 2.5% or less, 2.0% or less, 1.5% or less, or 1.0% or less in that order.

The oxide-based glass composition may, or may not, contain one or more rare earth oxides other than those mentioned above, such as Lu₂O₃ or Sc₂O₃. Because these components are generally expensive components, the content of a rare earth oxide other than La₂O₃, Y₂O₃ and Gd₂O₃ (the total content of these if two or more types thereof are contained) is preferably 2.5% or less, is more preferably 1.5% or less, 1.0% or less or 0.5% or less, and can be 0%.

From the perspective of improving weathering resistance, the total content of Al₂O₃, La₂O₃, Y₂O₃ and Gd₂O₃ (Al₂O₃+La₂O₃+Y₂O₃+Gd₂O₃) in Glasses 1 to 6 is preferably 0.1% or more, and is more preferably 0.15% or more, 0.20% or more, 0.25% or more, 0.30% or more, 0.35% or more, 0.40% or more, 0.45% or more, or 0.50% or more in that order. On the other hand, from the perspectives of ensuring the thermal stability of the glass and/or lowering the melting temperature of the glass, the total content (Al₂O₃+La₂O₃+Y₂O₃+Gd₂O₃) is preferably 8.0% or less, and is more preferably 7.0% or less, 6.5% or less, 6.0% or less, 5.5% or less, 5.0% or less, 4.5% or less, 4.0% or less, 3.5% or less, 3.0% or less, 2.5% or less, 2.0% or less, 1.5% or less or 1.0% or less in that order.

If cations having a nominal valency of +2 are seen in the overall glass composition, it tends to be difficult to achieve prominent effects in terms of weathering resistance and improving the transmittance of light in the visible region. Therefore, the total content of MgO, CaO, SrO and BaO, which are oxides of cations having a nominal valency of +2, is preferably such that the molar ratio relative to the content of Li₂O ((MgO+CaO+SrO+BaO)/Li₂O), which is an oxide of Li ions, which are essential cations, is 2.0 or less, and is more preferably 1.5 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1.0 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less or 0.2 or less. As mentioned later, the components mentioned above are optional components that can be used together with some alkali components in order to adjust the half value.

In addition, the total content of MgO, CaO, SrO, BaO and ZnO, which are oxides of cations having a nominal valency of +2, is preferably such that the molar ratio relative to the content of Li₂O ((MgO+CaO+SrO+BaO+ZnO)/Li₂O), which is an oxide of Li ions, which are essential cations, is 2.0 or less, and is more preferably 1.5 or less, 1.3 or less, 1.2 or less, 1.1 or less, 1.0 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less or 0.2 or less from the perspective of improving the transmittance of light in the visible region. On the other hand, from the perspective of improving weathering resistance, the value of (MgO+CaO+SrO+BaO+ZnO)/Li₂O) is preferably 2.0 or more, and is more preferably 2.5 or more, 3.0 or more, 3.5 or more, or 4.0 or more in that order. As mentioned later, the components mentioned above are optional components that can be used together with some alkali components in order to adjust the half value.

The content of BaO can be 0%, 0% or more, or more than 0%. BaO is a component that can increase weathering resistance when introduced at a certain quantity, and causes little change in the value of T600 when introduced. T600 will be explained later. BaO can be added in order to increase the thermal stability of the glass and adjust the meltability of the glass. In addition, BaO can be used in order to adjust the concentration of CuO. The content of BaO is preferably 0.5% or more, and is more preferably 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, 4.0% or more, 4.5% or more, 5.0% or more, 5.5% or more, 6.0% or more, 6.5% or more, or 7.0% or more in that order. However, excessive introduction tends to lead to a decrease in the value of T400. T400 will be explained later. From the perspectives mentioned above, the content of BaO is preferably 36.0% or less, and is more preferably 35.0% or less, 34.0% or less, 33.0% or less, 32.0% or less, 31.0% or less, 30.0% or less, 29.0% or less, 28.0% or less, 27.0% or less, 26.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 23.0% or less, 22.0% or less, 21.0% or less, 20.0% or less, 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, or 9.0% or less in that order.

The content of SrO can be 0%, 0% or more, or more than 0%. Like BaO, SrO is a component that is unlikely to lower weathering resistance, and is a component that can be added, as appropriate, for reasons such as adjusting the thermal stability of the glass, and the like. SrO can also be used in order to adjust to the concentration of CuO. The content of SrO is preferably 0.5% or more, and is more preferably 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, 4.0% or more, 4.5% or more, 5.0% or more, 5.5% or more, 6.0% or more, 6.5% or more, or 7.0% or more in that order. However, because excessive introduction tends to lead to a decrease in the value of T400, the content of SrO is preferably 30.0% or less, and is more preferably 29.0% or less, 28.0% or less, 27.0% or less, 26.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 23.0% or less, 22.0% or less, 21.0% or less, 20.0% or less, 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, or 9.0% or less in that order.

The content of CaO can be 0%, 0% or more, or more than 0%. CaO is a component that is unlikely to lower weathering resistance, and is a component that can be added, as appropriate, for reasons such as adjusting the thermal stability of the glass, and the like. CaO can also be used in order to adjust to the concentration of CuO. The content of CaO is preferably 0.5% or more, and is more preferably 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, 4.0% or more, 4.5% or more, 5.0% or more, 5.5% or more, 6.0% or more, 6.5% or more, or 7.0% or more in that order. However, because excessive introduction tends to lead to a decrease in the value of T400, the content of CaO is preferably 30.0% or less, and is more preferably 29.0% or less, 28.0% or less, 27.0% or less, 26.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 23.0% or less, 22.0% or less, 21.0% or less, 20.0% or less, 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, or 9.0% or less in that order.

Among the cations included in the main cation group mentioned above, Na ions, K ions and Zn ions tend to cause a deterioration in the weathering resistance of the glass, and it is therefore difficult to freely use these ions instead of Li ions, which are essential cations. From the additional perspective of improving the transmittance of light in the visible region or near-infrared region, the ratio of the total content of Na₂O, K₂O and ZnO relative to the content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) in Glasses 1 to 6 is 2.4 or less, is preferably 2.3 or less, is more preferably 2.2 or less, 2.1 or less, 2.0 or less, 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, 1.1 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, 0.1 or less or 0.05 or less in that order, and can be 0.00. On the other hand, from the perspective of lowering raw material costs of the glass, the molar ratio ((Na₂O+K₂O+ZnO)/Li₂O) can be 0, 0 or more, or more than 0, and is preferably 0.05 or more, and can be 0.1 or more, 0.2 or more or 0.3 or more, from the perspective of facilitating a decrease in the value of Tg or Tm, which are explained later, by mixing a plurality of components.

In addition, it becomes difficult to introduce a large quantity of P₂O₅ in order to maintain weathering resistance as the content of Na ions, K ions and Zn ions increases, and it is therefore difficult to introduce a required amount of P₂O₅. From these perspectives and the perspective of suppressing a reduction in weathering resistance such as that mentioned above, the total content of Na₂O, K₂O and ZnO (Na₂O+K₂O+ZnO) is preferably 30.0% or less, and is more preferably 25.0% or less, 20.0% or less, 15.0% or less, 12.0% or less, 10.0% or less, 9.0% or less, 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, 2.0% or less, or 1.0% or less in that order. The above total content can be 0%. On the other hand, from the perspective of lowering raw material costs of the glass, the total content (Na₂O+K₂O+ZnO) can be 1.0% or more, 2.0% or more, 3.0% or more or 5.0% or more.

The content of Na₂O can be 0%, 0% or more, or more than 0%. Na₂O, if introduced excessively, tends to cause a decrease in weathering resistance. Therefore, the content of Na₂O is preferably 20.0% or less, and is more preferably 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, 9.0% or less, or 8.0% or less in that order. On the other hand, because Na₂O is a raw material that can be easily and inexpensively procured, and can be added, as appropriate, in order to improve meltability, the content of Na₂O can be, for example, 0.5% or more, and can be 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, 4.0% or more, or 5.0% or more.

The content of K₂O can be 0%, 0% or more, or more than 0%. K₂O, if introduced excessively, also tends to cause a decrease in weathering resistance. Furthermore, it is preferable not to actively introduce K₂O, which tends to shift absorption by CuO to the short wavelength side. From these perspectives, the content of K₂O is preferably 20.0% or less, and is more preferably 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, 9.0% or less, or 8.0% or less in that order. On the other hand, K₂O can be added, as appropriate, in order to improve the meltability of the glass. From this perspective, the content of K₂O is preferably 0.2% or more, and is more preferably 0.5% or more, 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, 4.0% or more, or 5.0% or more in that order.

The content of Cs₂O can be 0%, 0% or more, or more than 0%. It is preferable not to actively introduce Cs₂O, which tends to cause a decrease in weathering resistance. The content of Cs₂O is more preferably 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, 9.0% or less, 8.0% or less, 7.0% or less, or 6.0% or less in that order. On the other hand, in order to adjust thermal stability and meltability, the content of Cs₂O can be 0.5% or more, and can be 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, or 4.0% or more.

From the perspective of increasing the meltability of the glass, the total content of Li₂O, Na₂O and K₂O (Li₂O+Na₂O+K₂O) is preferably 1.8% or more, and is more preferably 2.1% or more, 2.3% or more, 2.5% or more, 3.5% or more, 4.5% or more, 5.5% or more, 6.5% or more, 7.5% or more, 8.5% or more, 9.5% or more, 10.0% or more, or 10.5% or more in that order.

On the other hand, from the perspective of further suppressing a decrease in weathering resistance, the total content (Li₂O+Na₂O+K₂O) is preferably 35.0% or less, and is more preferably 33.5% or less, 32.5% or less, 31.5% or less, 30.5% or less, 29.5% or less, 28.5% or less, 27.5% or less, 26.5% or less, 25.5% or less, 24.5% or less, 23.5% or less, 21.5% or less, 20.5% or less, 19.5% or less, 18.5% or less, 17.5% or less, 16.6% or less, 15.5% or less, 14.5% or less, or 13.5% or less in that order. It is preferable for the total content (Li₂O+Na₂O+K₂O) to be not higher than the values mentioned above from the perspectives of preventing the occurrence of chipping and cracking in the glass as a result of stress exerted on the glass when the amount of expansion and shrinkage of the glass, which is caused by an increase in the coefficient of thermal expansion, increases and a change in volume of the glass is suppressed by another member.

From the perspective of suppressing deliquescence of the glass, the total content of Na₂O and K₂O (Na₂O+K₂O) is preferably 30.0% or less, and is more preferably 29.0% or less, 28.0% or less, 27.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 23.0% or less, 22.0% or less, 21.0% or less, 20.0% or less, 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, 9.0% or less, 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, 4.0% or less, 3.0% or less, 2.0%% or less, 1.0% or less, or 0.5% or less in that order. By setting the total content of Na₂O and K₂O (Na₂O+K₂O) to be 0%, it is possible to obtain a glass having further reduced deliquescence. On the other hand, from the perspective of lowering raw material costs of the glass while suppressing meltability of the glass and suppressing a decrease in the value of T600, the total content (Na₂O+K₂O) can be 1.0% or more, and can be 2.0% or more, 3.0% or more, 4.0% or more, 5.0% or more, 6.0% or more, 7.0% or more, 8.0% or more, 9.0% or more, 10.0% or more, 11.0% or more, 12.0% or more, 13.0% or more, 14.0% or more, or 15.0% or more.

CuO can be replaced with other components in order to adjust the thickness of the glass, but on such occasion, by forming a glass in which the total content of Na₂O, K₂O, CaO, SrO and BaO (Na₂O+K₂O+CaO+SrO+BaO) is 0% or more, it is possible to adjust the concentration of CuO without greatly altering the position of near-infrared absorption. The total content (Na₂O+K₂O+CaO+SrO+BaO) is preferably 0.5% or more, and is more preferably 1.0% or more, 1.5% or more, 2.0% or more, 2.5% or more, 3.0% or more, 3.5% or more, 4.0% or more, 4.5% or more, 5.0% or more, 5.5% or more, 6.0% or more, 6.5% or more, or 7.0% or more in that order. However, because excessive introduction tends to lead to a decrease in the value of T400, the total content (Na₂O+K₂O+CaO+SrO+BaO) is preferably 36.0% or less, and is more preferably 35.0% or less, 34.0% or less, 33.0% or less, 32.0% or less, 31.0% or less, 30.0% or less, 29.0% or less, 28.0% or less, 27.0% or less, 26.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 23.0% or less, 22.0% or less, 21.0% or less, 20.0% or less, 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, or 9.0% or less in that order. From the perspective of maximizing the near-infrared absorption characteristics of the glass, the total content (Na₂O+K₂O+CaO+SrO+BaO) can be 8.0% or less, 7.0% or less, 6.0% or less, 5.0% or less, or 4.0% or less.

With regard to weathering resistance, the matter that deliquescence in the glass is reduced and/or the matter that the occurrence of precipitates at the surface of the glass is suppressed in high temperature high humidity environments can be used as an indicator of weathering resistance. This is explained later. In order to further improve weathering resistance, it is more preferable to introduce Al₂O₃, and it is preferable to then introduce one or more of Y₂O₃, La₂O₃ and Gd₂O₃. In addition, BaO can improve the weathering resistance if introduced at a relatively large quantity, and SrO and CaO need to be introduced at an even larger quantity from the perspective of improving weathering resistance, and a value calculated as “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” (units: mol %) is preferably 0% or more, is more preferably more than 0%, and is preferably 0.5% or more, 1.0% or more, 2.0% or more, 3.0% or more, 4.0% or more, 5.0% or more, 6.0% or more, 7.0% or more, or 8.0% or more. If emphasis is to be placed on the weathering resistance and mechanical strength of the glass, this value is more preferably 9.0% or more, 10.0% or more, 11.0% or more, 12.0% or more, 13.0% or more, 14.0% or more, 15.0% or more, 16.0% or more, 17.0% or more, 18.0% or more, or 19.0% or more in that order. In the expression “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)”, “Al₂O₃” denotes the content of Al₂O₃, “Y₂O₃” denotes the content of Y₂O₃, “La₂O₃” denotes the content of La₂O₃, “Gd₂O₃” denotes the content of Gd₂O₃, “BaO” denotes the content of BaO, “CaO” denotes the content of CaO, and “SrO” denotes the content of SrO. That is, the expression “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” is the sum of a value calculated by multiplying the content of Al₂O₃ by 3, the content of Y₂O₃, the content of La₂O₃, the content of Gd₂O₃, a value calculated by dividing the content of BaO by 3, and a value calculated by dividing the sum of the content of CaO and the content of SrO by 6, and units for the thus calculated value are % (mol %).

On the other hand, a glass in which the value of “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” is excessively high tends to be poor in terms of meltability and tends to be such that the position of near-infrared absorption shifts towards the visible light side, and the value calculated as “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” is therefore preferably 40.0% or less, and is more preferably 37.0% or less, 35.0% or less, 33.0% or less, 32.0% or less, 30.0% or less, 28.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 23.0% or less, 22.0% or less or 21.0% or less in that order.

The ratio of the value calculated as “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” relative to the total content of P₂O₅, Li₂O and CuO, that is, “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)/(P₂O₅+Li₂O+CuO)” can be 0.0 or more. Components selected from the group consisting of Al₂O₃, Y₂O₃, La₂O₃, Gd₂O₃, BaO, CaO and SrO are preferably introduced at a certain quantity or more relative to the quantity of P₂O₅, Li₂O and CuO, which are essential components. Therefore, the above ratio is preferably 0.01 or more, and is more preferably 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, or 0.09 or more in that order. If weathering resistance is to be further increased, the above ratio is more preferably 0.10 or more, and is further preferably 0.11 or more, 0.12 or more, 0.13 or more, 0.14 or more, 0.15 or more, 0.16 or more, 0.17 or more, 0.18 or more, 0.19 or more, 0.20 or more, 0.21 or more, 0.22 or more, 0.23 or more, 0.24 or more, or 0.25 or more in that order.

On the other hand, because the transmittance characteristics of the glass decrease and the tendency for the stability of the glass to decrease becomes stronger if the above ratio is excessively high, the above ratio is preferably 0.36 or less, and is more preferably 0.35 or less, 0.34 or less, 0.33 or less, 0.32 or less, 0.31 or less, 0.30 or less, 0.29 or less or 0.28 or less in that order.

The content of ZnO can be 0%, 0% or more, or more than 0%. ZnO is a component that can be added, as appropriate, for reasons such as adjusting the thermal stability of the glass, and the like, but from the perspective that ZnO tends to cause a decrease in the weathering resistance of the glass and the perspective of ensuring that the introduced amount of P₂O₅, which is an essential component, is sufficient, the upper limit for the content thereof is preferably 20.0% or less, and is more preferably 19.0% or less, 18.0% or less, 17.0% or less, 16.0% or less, 15.0% or less, 14.0% or less, 13.0% or less, 12.0% or less, 11.0% or less, 10.0% or less, 9.0% or less, 8.0% or less, 7.0% or less, 6.0% or less or 5.0% or less in that order. If the effect of introducing another component is a priority, the content of ZnO can be 4.0% or less, 3.0% or less, 2.0% or less, or 1.0% or less. On the other hand, if ZnO is introduced in order to adjust the thermal stability of the glass and lower the value of Tg and/or Tm, the content of ZnO is more preferably 0.4% or more, 0.6% or more, 0.8% or more, 1.0% or more, 1.2% or more, 1.4% or more, 1.6% or more, 1.8% or more or 2.0% or more in that order.

The above glass is preferably constituted essentially from the components mentioned above, but may contain other components as long as the operational effects achieved by the components mentioned above are not impaired. In addition, inclusion of unavoidable impurities in the glass is not excluded.

For example, Nb₂O₅ and ZrO₂ can be introduced, as appropriate, respectively, at quantities of more than 0%, 0.1% or more, or 0.2% or more, as components other than the components mentioned above in order to adjust the weathering resistance and mechanical strength and improve the thermal stability of the glass, but the content of each of these components is preferably 5.0% or less, and are more preferably 4.0% or less, 3.0% or less, 2.0% or less, 1.0% or less, 0.5% or less or 0.3% or less in that order. The content of each of these components can be 0%.

TiO₂, WO₃ and Bi₂O₃ can be introduced, as appropriate to the extent that the transmittance of glass is not affected, respectively, at quantities of more than 0%, 0.1% or more, or 0.2% or more, as components other than the components mentioned above in order to adjust the weathering resistance and mechanical strength and improve the thermal stability of the glass, but the content of each of these components is preferably 4.0% or less, and are more preferably 3.0% or less, 2.0% or less, 1.0% or less, 0.5% or less or 0.3% or less in that order. The content of each of these components can be 0%.

Pb, As, Cd, TI, Be and Se are all toxic. Therefore, it is preferable for the above glass not to contain these as glass components.

U, Th and Ra are all radioactive elements. Therefore, it is preferable for the above glass not to contain these as glass components.

V, Cr, Mn, Fe, Co, Ni, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er and Tm increase coloration of a glass and can be a source of fluorescence. Therefore, in the above glass, the total content on an oxide basis of these elements in the oxide-based glass is preferably 10 ppm by mass or less, and it is more preferable for these elements not to be contained as glass components.

Of these, V₂O₅ is preferably not used due to being toxic. In one embodiment, Glasses 1 to 6 are preferably glasses that do not contain V ions, and the content (on an oxide basis) of V₂O₅ in the oxide-based glass composition is preferably 1.0% or less, is more preferably 0.3% or less, 0.1% or less and 0.01% or less in that order, and it is more preferable for these glasses to contain no V₂O₅.

As one example, the ratio of V₂O₅ and Li₂O, which is an essential component, is such that the ratio of the content of V₂O₅ relative to the content of Li₂O (V₂O₅/Li₂O) is preferably 0.0080 or less, and is more preferably 0.0048 or less, 0.0028 or less, 0.0018 or less or 0.0014 or less in that order.

CoO causes a decrease in the transmittance of light in the visible region of the glass, and is toxic, and is therefore preferably not used. In one embodiment, Glasses 1 to 6 are preferably glasses that do not contain Co ions, and it is preferable for the oxide-based glass composition to contain no CoO.

Raw materials for introducing Ge and Ta into the glass are expensive. Therefore, it is preferable for the above glass not to contain these as glass components.

Sb (Sb₂O₃), Sn (SnO₂), Ce (CeO₂) and SO₃ are elements that can be optionally added as clarifying agents. Of these, Sb (Sb₂O₃) is a clarifying agent having a high clarifying effect.

Sn (SnO₂) and Ce (CeO₂) have a lower clarifying effect than Sb (Sb₂O₃). These clarifying agents, if added at large quantities, tend to enhance coloration of the glass. Therefore, in a case where a clarifying agent is added, it is preferable to add Sb (Sb₂O₃) in view of the effect on coloration caused by the addition.

The content values of the components listed below that are able to function as clarifying agents are expressed as oxide-based values in the glass composition.

The content of Sb₂O₃ is expressed as an outer percentage. That is, if the total content as oxides of all glass components other than Sb₂O₃, SnO₂, CeO₂ and SO₃ is taken to be 100.0 mass %, the content of Sb₂O₃ is preferably less than 2.0 mass %, and is more preferably 1.5 mass % or less, 1.2 mass % or less, 1.0 mass % or less, 0.9 mass % or less, 0.8 mass % or less, 0.7 mass % or less, 0.6 mass % or less, 0.5 mass % or less, 0.4 mass % or less, 0.3 mass % or less, 0.2 mass % or less or less than 0.1 mass % in that order. The content of Sb₂O₃ may be 0 mass %. However, from the perspectives of facilitating oxidation of the glass and increasing the transmittance of light in the visible region, the content of Sb₂O₃ can be 0.01 mass % or more, and can be 0.02 mass % or more, 0.03 mass % or more, 0.04 mass % or more, 0.05 mass % or more, 0.06 mass % or more, or 0.08 mass % or more.

The content of SnO₂ is also expressed as an outer percentage. That is, if the total content as oxides of all glass components other than SnO₂, Sb₂O₃, CeO₂ and SO₃ is taken to be 100.0 mass %, the content of SnO₂ is preferably less than 2.0 mass % or less than 1.0 mass %, and is more preferably 0.9 mass % or less, 0.8 mass % or less, 0.7 mass % or less, 0.6 mass % or less, 0.5 mass % or less, 0.4 mass % or less, 0.3 mass % or less, 0.2 mass % or less or 0.1 mass % in that order. The content of SnO₂ may be 0 mass %. If the content of SnO₂ falls within the range mentioned above, it is possible to improve the clarity of the glass.

The content of CeO₂ is also expressed as an outer percentage. That is, if the total content as oxides of all glass components other than CeO₂, Sb₂O₃, SnO₂ and SO₃ is taken to be 100.0 mass %, the content of CeO₂ is preferably less than 2.0 mass % or less than 1.0 mass %, and is more preferably 0.9 mass % or less, 0.8 mass % or less, 0.7 mass % or less, 0.6 mass % or less, 0.5 mass % or less, 0.4 mass % or less, 0.3 mass % or less, 0.2 mass % or less or less than 0.1 mass % in that order. The content of CeO₂ may be 0 mass %. If the content of CeO₂ falls within the range mentioned above, it is possible to improve the clarity of the glass.

The content of SO₃ is also expressed as an outer percentage. That is, if the total content as oxides of all glass components other than SO₃, Sb₂O₃, SnO₂ and CeO₂ is taken to be 100.0 mass %, the content of SO₃ is preferably less than 2.0 mass %, more preferably less than 1.0 mass %, further preferably less than 0.5 mass %, and yet more preferably less than 0.1 mass %. The content of SO₃ may be 0 mass %. If the content of SO₃ falls within the range mentioned above, it is possible to improve the clarity of the glass.

<Physical Properties of Glass>

(Transmittance Characteristics)

The above glass is suitable for use as a glass for a near-infrared cut filter. In the present invention and the present description, the term “transmittance” means external transmittance including reflection losses, unless explicitly indicated otherwise.

The half value Δ_(T)50, which is the wavelength at which the transmittance becomes 50% at a wavelength of 550 nm or longer, the transmittance T1200 at a wavelength of 1200 nm, the average transmittance value within the wavelength range from 1100 nm to 800 nm (referred to as “Ave.T1100-800”), and the transmittance T750 at a wavelength of 750 nm can be used as indicators of near-infrared cutting performance.

In addition, the above glass can exhibit high transmittance of light in the visible region. The transmittance T400 at a wavelength of 400 nm and the transmittance T600 at a wavelength of 600 nm can be used as indicators of transmittance of light in the visible region.

Transmittance characteristics of the glass are determined using the methods described below.

A glass sample is processed so as to have optically polished flat surfaces that are parallel to each other, and external transmittance is measured at wavelengths of 200 to 1200 nm. The external transmittance includes reflection losses of light rays at the sample surface.

The intensity of light rays incident perpendicularly to one of the optically polished flat surfaces is denoted by the intensity A, and the intensity of light rays emitted from the other flat surface is denoted by the intensity B, and the spectral transmittance including reflection losses is calculated as the value of B/A. The wavelength at which the spectral transmittance becomes 50% at a wavelength of 550 nm or longer is taken to be the half value Δ_(T)50. The spectral transmittance at a wavelength of 400 nm is denoted by T400, the spectral transmittance at a wavelength of 600 nm is denoted by T600, and the spectral transmittance at a wavelength of 1200 nm is denoted by T1200. The average value of the spectral transmittance within the wavelength range from 1100 nm to 800 nm is denoted by Ave.T1100-800, and the spectral transmittance at a wavelength of 750 nm is denoted by T750. In addition, in a case where a glass to be measured is not a glass having a thickness to be calculated, the thickness of the glass is denoted by d, the transmittance at each wavelength λ is calculated using Equation A below, and calculated values can be determined from spectral transmittance values obtained from the calculations.

T(λ)=(1−R(λ))²×exp(log_(e)((T ₀(λ)/100)/(1−R(λ))²)×d/d ₀)×100  Equation A:

In Equation A, T(λ) denotes the transmittance (%) calculated for a wavelength Δ, T₀(λ) denotes the measured transmittance (%) at the wavelength Δ, d denotes the thickness (mm) to be calculated, do denotes the thickness of the glass (mm), R(λ) denotes the reflectance at the wavelength Δ, which is represented by ((n(λ)−1)/(n(λ)+1))², and n(λ) denotes the refractive index at the wavelength Δ. Here, calculations are performed using the constants n(λ)=1.51680 and R(λ)=0.042165.

If the value of T600, which is the transmittance of light in the red region, is high and the value of T1200, which is the transmittance of light in the near-infrared region, is low, this can mean that the transmittance of light in the visible region is improved and near-infrared cutting performance is also improved. In addition, if the value of T400, which is the transmittance of light in the violet region, is high, this can mean that the transmittance of light in the visible region is improved.

From the perspectives mentioned above, preferred ranges for the values of T400, T600 and T1200 are as indicated below.

The value of T400 is preferably 70% or more, and is more preferably 71% or more, 72% or more, 73% or more, 74% or more, 75% or more, 76% or more, 77% or more, 78% or more, 79% or more, or 80% or more in that order. The value of T400 can be, for example, 98% or less, 97% or less or 96% or less, but because a high T400 value can mean superior transmittance of light in the visible region, it is preferable for this value to be higher than the values shown above.

The value of T600 is preferably 50% or more, and is more preferably 55% or more, 56%, 57% or more, 58% or more, 59% or more, 60% or more, 61% or more, 62% or more, 63% or more, 64% or more, 65% or more, 66% or more, 67% or more, 68% or more, 69% or more, 70% or more, 71% or more, 72% or more, 73% or more, 74% or more, or 75% or more in that order. The value of T600 can be, for example, 90% or less, 85% or less or 80% or less, but because a high T600 value can mean superior transmittance of light in the visible region, it is preferable for this value to be higher than the values shown above.

The value of T1200 is preferably 30% or less, and is more preferably 29% or less, 28% or less, 27% or less, 26% or less, 25% or less, 24% or less, 23% or less, 22% or less, 21% or less, 20% or less, 19% or less, 18% or less, 17% or less, 16% or less, 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, or 1% or less in that order. In order to also achieve the transmittance of light in the visible region, the value of T1200 can be, for example, 1% or more, 3% or more, 5% or more or 7% or more, but because a low T1200 value can mean superior near-infrared cutting performance, it is preferable for this value to be lower than the values shown above.

In one embodiment, the value of T1200 can be β1% or less.

β1 is calculated using Equation B1 below. In Equation B1, R is the O/P ratio.

β1=64×R−170  (Equation B1)

In one embodiment, T1200 can be not higher than a numerical value (units: %) represented by β2, β3, β4, β5 or β6, which are shown in Equations B2 to B6 below. In the equations below, R is the O/P ratio.

β2=64×R−175  Equation B2:

β3=64×R−180  Equation B3:

β4=80×R−220  Equation B4:

β5=80×R−224  Equation B5:

β6=80×R−228  Equation B6:

The half value Δ_(T)50, which is the wavelength at which the spectral transmittance becomes 50% at a wavelength of 550 nm or longer, is preferably 600 nm or more, and is more preferably 610 nm or more, 613 nm or more, 615 nm or more, 617 nm or more, 620 nm or more, 623 nm or more, 625 nm or more, or 628 nm or more in that order. The half value Δ_(T)50 is preferably 650 nm or less, and is more preferably 647 nm or less, 645 nm or less, 643 nm or less, 641 nm or less, 640 nm or less, 639 nm or less, or 638 nm or less in that order. Being able to achieve the half value Δ_(T)50, which is the wavelength at which the transmittance becomes 50% at a wavelength of 550 nm or longer, at a prescribed glass thickness or less is preferable from the perspective of achieving both reducing the thickness of the glass and improving near-infrared cutting performance. A prescribed glass thickness or less is preferably a thickness of 0.25 mm or less.

In addition, because the above glass exhibits excellent near-infrared absorption characteristics, the value of “Ave.T1100-800” can be suppressed to 15% or less. The value of “Ave.T1100-800” is preferably 14% or less, and is more preferably 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1.3% or less, 1.0% or less, 0.3% or less, 0.1% or less, 0.03% or less, or 0.01% or less in that order.

In addition, because the above glass exhibits excellent near-infrared absorption characteristics, the value of T750 can be suppressed to 25% or less. The value of T750 is preferably 24% or less, and is more preferably 23% or less, 22% or less, 21% or less, 20% or less, 19% or less, 18% or less, 17% or less, 16% or less, 15% or less, 14% or less, 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1.3% or less, 1.0% or less, 0.3% or less, 0.1% or less, 0.03% or less, or 0.01% or less in that order.

In one embodiment, the above glass can be used as a glass for a near-infrared cut filter having a thickness of 0.25 mm or less, as described in detail below.

For the above glass, characteristics (a) to (h) below can be given as transmittance characteristics that are preferred for a thin glass for a near-infrared cut filter having a thickness of 0.25 mm or less. The above glass preferably satisfies one or more of characteristics (a) to (h) below, and can satisfy two or more of these characteristics. By adjusting the glass composition in the manner explained above, it is possible to obtain a glass having preferred transmittance characteristics.

-   -   (a) A glass for which the wavelength Δ_(T)50, at which the         external transmittance including reflection losses becomes 50%         at a wavelength of 550 nm or longer, is 633 nm has a thickness         of 0.25 mm or less, and     -   at this thickness, the external transmittance T600 including         reflection losses at a wavelength of 600 nm is 50% or more, and         the external transmittance T1200 including reflection losses at         a wavelength of 1200 nm is 30% or less.

For characteristic (a), a glass for which the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm has a thickness of 0.25 mm or less, and it is more preferable that the above thickness is within the thickness range described later for the thickness of a near-infrared cut filter. This is applied to characteristics (b), (e) and (f) below.

(b) A glass for which the wavelength at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer is 633 nm has a thickness of 0.25 mm or less, and at this thickness, the external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is β1% or less. β is calculated from Equation B1 below. In Equation B1, R is the O/P ratio in the above glass.

β1=64×R−170  (Equation B1)

As mentioned above, the value of T1200 can be β2% or less, β3% or less, β4% or less, β5% or less, or β6% or less.

(c) As transmittance characteristics calculated at a thickness of 0.11 mm, the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50%, falls within the range 600 nm to 650 nm, the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 30% or less, and the external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.

(d) As transmittance characteristics calculated at a thickness of 0.21 mm, the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50%, falls within the range 600 nm to 650 nm, the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 25% or less, and the external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.

(e) A glass for which the wavelength at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer is 645 nm has a thickness of 0.25 mm or less, and

-   -   at this thickness, the external transmittance T600 including         reflection losses at a wavelength of 600 nm is 50% or more, and         the external transmittance T1200 including reflection losses at         a wavelength of 1200 nm is 30% or less.

(f) A glass for which the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm has a thickness of 0.25 mm or less, and

-   -   at this thickness, the external transmittance T600 including         reflection losses at a wavelength of 600 nm is 50% or more, the         external transmittance T1200 including reflection losses at a         wavelength of 1200 nm is β1% or less, and β1 is a value         calculated using Equation 4 above.

(g) As transmittance characteristics calculated at a thickness of 0.23 mm, the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50%, falls within the range 600 nm to 650 nm, the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 18% or less, and the external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.

(h) As transmittance characteristics calculated at a thickness of 0.25 mm, the wavelength Δ_(T)50, at which the external transmittance including reflection losses becomes 50%, falls within the range 600 nm to 650 nm, the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 16% or less, and the external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.

(Weathering Resistance)

The above glass can exhibit excellent weathering resistance by having the composition described above. Examples of indicators for weathering resistance can include weathering resistance evaluation results evaluated by eye using a method that is described in Examples section below, and any of evaluation results S to D are preferred, any of the evaluation results S to C are more preferred, any of evaluation results S to B are further preferred, evaluation results S and A are yet more preferred, and evaluation result S is further preferred.

Furthermore, haze value measured using a haze meter can also be used as an indicator of weathering resistance. A glass having a haze value of 15% or less can be given as an example of a glass having further superior weathering resistance.

For weathering resistance, a glass which has an evaluation result of S or A (and especially S) when evaluated by eye using the method mentioned above and which has a haze value, as measured using a haze meter, of 15% or less is yet more preferred.

(Glass Transition Temperature Tg and Temperature Tm at which an Endothermic Reaction Concludes Due to Melting)

The glass transition temperature of the above glass is not particularly limited. From the perspective of increasing the transmittance of light in the short wavelength region of the glass by improving the meltability of the glass and reducing the burden on an annealing furnace or molding device, the Tg value is preferably 450° C. or lower, and is more preferably 440° C. or lower, 430° C. or lower, 420° C. or lower, 410° C. or lower, or 400° C. or lower in that order. From the perspective of increasing the chemical durability and/or heat resistance of the glass, the Tg value is preferably 250° C. or higher, and is more preferably 260° C. or higher, 270° C. or higher, 280° C. or higher, 290° C. or higher, or 300° C. or higher in that order.

The Tg value of the glass can be controlled by adjusting the content of Li₂O, Na₂O or K₂O or the total content of these, or by adjusting the content of ZnO, the content of MgO, the content of Al₂O₃ or the total content of these.

The Tm value, which is the temperature at which an endothermic reaction concludes due to melting, is not particularly limited. As the Tm value decreases, meltability improves and devitrification is less likely to occur even if molding is carried out at a higher viscosity. In addition, as the meltability of the glass improves, it tends to be possible to increase transmittance by the glass of visible light in the short wavelength region. From these perspectives, the Tm value is preferably 890° C. or lower, and is more preferably 880° C. or lower, 870° C. or lower, 860° C. or lower, 850° C. or lower, 840° C. or lower, 830° C. or lower, 820° C. or lower, 810° C. or lower, 800° C. or lower, 790° C. or lower, 780° C. or lower, 770° C. or lower, 760° C. or lower, 750° C. or lower, 740° C. or lower, 730° C. or lower, 720° C. or lower, 710° C. or lower, 700° C. or lower, 690° C. or lower, 680° C. or lower, 670° C. or lower, 660° C. or lower, or 650° C. or lower in that order. The lower limit of the Tm value is not particularly limited, but because the weathering resistance of the glass tends to deteriorate if the Tm value is too low, the Tm value can be 500° C. or higher, 550° C. or higher, 580° C. or higher, 600° C. or higher, 620° C. or higher, or 640° C. or higher.

The Tm value of the glass can be controlled by adjusting the content of Li₂O, Na₂O or K₂O or the total content of these, or by adjusting the content of ZnO, the content of MgO, the content of Al₂O₃ or the total content of these.

(Specific Gravity)

The near-infrared cut filter is preferably lightweight in order to reduce the weight of an element or device in which the filter is incorporated. From this perspective, the specific gravity of the above glass is preferably 3.40 or less, and is more preferably 3.35 or less, 3.30 or less, 3.25 or less, 3.20 or less, 3.15 or less, 3.10 or less, 3.05 or less, 3.00 or less, 2.95 or less, 2.90 or less, 2.85 or less, 2.80 or less, 2.75 or less, 2.70 or less, 2.65 or less, or 2.60 or less in that order.

The specific gravity can be, for example, 2.0 or more or 2.4 or more, but because a low specific gravity is preferred from the perspective mentioned above, it is preferable for the specific gravity to be lower than the values listed above.

(Molar Volume)

The molar volume (M/D) of the glass is not particularly limited. From the perspective of increasing near-infrared absorption capacity by increasing the amount of CuO per unit volume, the molar volume of the glass is preferably lower. The molar volume can be lowered by replacing P₂O₅, La₂O₃, Y₂O₃, Gd₂O₃, BaO, K₂O, or the like, with Li₂O, and can be somewhat lowered by replacing Al₂O₃, CuO or Na₂O with Li₂O. On the other hand, the molar volume does not significantly change if CaO, ZnO or SrO is replaced with Li₂O, and the molar volume tends to increase if MgO is replaced with Li₂O. In view of these tendencies, the molar volume of the glass can be adjusted by adjusting the glass composition. The molar volume is preferably 45 cc/mol or less, and is more preferably 43 cc/mol or less, 42 cc/mol or less, 41 cc/mol or less, 40 cc/mol or less, 39.5 cc/mol or less, 39.0 cc/mol or less, 38.5 cc/mol or less, 38.0 cc/mol or less, or 37.5 cc/mol or less in that order.

On the other hand, the molar volume can be increased from the perspective of maintaining the weathering resistance of the glass, and from this perspective, the molar volume of the above glass can be 34.0 cc/mol or more, and can be 35.0 cc/mol or more, 36.0 cc/mol or more, 36.5 cc/mol or more, 37.0 cc/mol or more, 37.5 cc/mol or more, 38.0 mol or more, 38.5 cc/mol or more, 39.0 cc/mol or more, or 39.5 cc/mol or more.

<Method for Producing Glass>

The above glass can be obtained by mixing, melting and molding the glass raw materials. For the production method, the following descriptions can also be referred.

The above near-infrared absorbing glass is suitable for use as a glass for a near-infrared cut filter. In addition, the above near-infrared absorbing glass can be used in optical elements (lenses and the like) in addition to a near-infrared cut filter, can also be used in a variety of glass products, and can be modified in various ways.

[Near-Infrared Cut Filter]

One aspect of the present invention relates to a near-infrared cut filter (hereinafter also referred to simply as a “filter”) comprised of the above near-infrared absorbing glass.

The glass that constitutes the above filter is as described above.

A specific example of a method for producing the above filter will be explained below. However, the production method described below is merely an example, and does not limit the present invention.

A molten glass is obtained by using glass raw materials such as phosphates, oxides, carbonates, nitrates, sulfates and fluorides as appropriate, the raw materials are weighed out so as to attain a prescribed composition, mixed, and then melted at a temperature of, for example, 800° C. to 1100° C. in a melting vessel such as a platinum crucible. During this process, a lid of platinum or the like can be used in order to suppress volatilization of volatile components. In addition, the melting can be carried out in air, and can also be carried out in an oxygen atmosphere or while bubbling oxygen into the molten glass in order to suppress changes in valency of Cu. A homogenized molten glass in which the amount of bubbles is reduced (and which preferably contains no bubbles) is obtained by agitating and clarifying the molten glass. A glass can be obtained after clarifying the glass at 900° C. to 1100° C. and then lowering the temperature of the glass 800° C. to 1000° C. in order to facilitate oxidation of the glass. However, it is not desirable for the melting temperature or clarification temperature to be lower than the liquidus temperature of the glass for a long period of time.

After agitating and clarifying the molten glass, the glass is poured out, gradually cooled, and then molded into a prescribed shape. It is preferable to pour the glass out after cooling the glass to a temperature close to the liquidus temperature and increasing the viscosity of the glass because convection is less likely to occur in the poured out glass and striation is less likely to occur. The gradual cooling speed can be selected within the range −50° C./hr to −1° C./hr, and can be −30° C./hr or −10° C./hr.

Well-known methods such as casting, pipe outflow, rolling and pressing can be used as the method for molding the glass. The molded glass is transferred to an annealing furnace that has been heated in advance to a temperature close to the transition temperature of the glass, and allowed to cool gradually to room temperature. A near-infrared cut filter can be produced in this way.

An example of a molding method will be explained below. A mold is prepared so as to be configured from: a flat horizontal bottom surface; a pair of side walls which face each other in parallel across the bottom surface; and a barrier plate which is positioned between the pair of side walls and blocks one opening part. A homogenized molten glass is poured into this mold from a platinum alloy pipe at a fixed outflow speed. The poured molten glass spreads inside the mold, and a glass plate is formed so as to have a fixed width that is regulated by the pair of side walls. The formed glass plate is continuously drawn from the opening of the mold. By appropriately specifying molding conditions such as the shape and dimensions of the mold and the outflow speed of the molten glass, it is possible to form a large, thick glass block. The molded glass body is transferred to an annealing furnace that has been heated in advance to a temperature close to the glass transition temperature of the molded body, and allowed to cool gradually to room temperature. The molded glass body, in which strain has been eliminated through gradual cooling, is subjected to mechanical processing such as slicing, grinding and polishing. In this way, it is possible to obtain a near-infrared cut filter having a shape that is suitable for an application, such as plate-shaped or lens-shaped. Alternatively, it is also possible to use a method comprising molding a preform from the above glass, and then heating, softening and press molding the preform (in particular, a precision press molding method comprising press molding a finished product without subjecting an optically functional surface to mechanical processing such as grinding or polishing). An optical multilayer film may, if necessary, be formed on a surface of the filter.

The above near-infrared cut filter can exhibit both excellent near-infrared cutting performance and high transmittance of light in the visible region. According to this near-infrared cut filter, the color sensitivity of a semiconductor image element can be favorably corrected.

In addition, the above near-infrared cut filter can also be combined with a semiconductor image sensor and used in an imaging device. A semiconductor image sensor is a product obtained by attaching a semiconductor image element such as a CCD or a CMOS in a package and then covering a light-receiving part with a translucent member. The near-infrared cut filter can also serve as the translucent member, or the translucent member and the near-infrared cut filter can be separate components.

The imaging device described above can comprise a lens for forming an image of a subject on a light-receiving surface of a semiconductor image sensor, or an optical element such as a prism.

According to the above near-infrared cut filter, it is possible to provide an imaging device in which color sensitivity correction can be favorably achieved and which can yield an image having excellent image quality.

In one embodiment, the above near-infrared cut filter can be a near-infrared cut filter having a thickness of 0.25 mm or less. With the appearance of smartphones in recent years, the trend for the camera thickness of image elements to become smaller has been remarkable, and this has led to demands for near-infrared cut filters to exhibit performance at lower thicknesses. The above near-infrared cut filter is suitable for use as this type of near-infrared cut filter. The thickness of the above near-infrared cut filter can be 0.24 mm or less, 0.23 mm or less, 0.22 mm or less, 0.21 mm or less, 0.20 mm or less, 0.19 mm or less, 0.18 mm or less, 0.17 mm or less, 0.16 mm or less, 0.15 mm or less, 0.14 mm or less, 0.13 mm or less, or 0.12 mm or less. The thickness of the above near-infrared cut filter can be, for example, 0.21 mm or 0.11 mm. In addition, the thickness of the above near-infrared cut filter can be, for example, 0.50 mm or more, but the thickness is not limited to this. In the present invention and the present description, the term “thickness” means the thickness of a sample in a region where transmittance is measured, and can be measured using a thickness gauge, a micrometer, or the like. For example, the thickness may be measured at the approximate center of a position through which transmitted light passes, or the thickness of multiple points within a spot of transmitted light may be measured, with the average value of these measurements used.

For transmittance characteristics of the above near-infrared cut filter, earlier descriptions relating to Glasses 1 to 6 can be referred. For physical properties of the above near-infrared cut filter, earlier descriptions relating to Glasses 1 to 6 can be referred.

EXAMPLES

The present invention will be explained in further detail below through the use of Examples. However, the present invention is not limited to embodiments in Examples.

Examples 1 to 66 and Comparative Examples X and A to D

As glass raw materials, phosphates, fluorides, carbonates, nitrates, oxides, and the like, were weighed out and mixed so as to obtain 150 g to 300 g of a glass having a composition shown in Table 1, the obtained mixture was placed in a platinum crucible or a quartz crucible, melted for 80 minutes to 100 minutes at 800° C. to 1000° C., defoamed and homogenized by being agitated, and then flowed onto a preheated mold and molded into a prescribed shape. The obtained glass molded body was transferred to an annealing furnace that had been heated to a temperature close to the glass transition temperature and gradually cooled to room temperature. A test piece was cut from the obtained glass, both surfaces of the test piece were polished to a mirror finish to attain a thickness of approximately 0.2 mm, and evaluations were then carried out using the following methods.

[Evaluation Methods]

<Transmittance Characteristics>

Transmittance of test pieces were measured at wavelengths of 200 to 1200 nm using a spectrophotometer. From the measurement results, half values (units: nm), T400, T600, T1200 and Ave.T1100-800 (units:%) were determined as values calculated at half values of 645 nm and 633 nm and calculated at thicknesses of 0.11 mm, 0.21 mm, 0.23 mm and 0.25 mm.

<Glass Transition Temperature Tg and Temperature Tm at which an Endothermic Reaction Concludes Due to Melting>

Using a differential scanning calorimeter produced by Rigaku (DSC8270), the glass transition temperature Tg and the temperature Tm at which an endothermic reaction concludes due to melting were measured at a temperature increase rate of 10° C./min. The measurement temperature range was from room temperature to 1050° C.

<Specific Gravity>

Specific gravity was measured using the Archimedes method.

<Molar Volume>

Molar volume was calculated from the measured specific gravity using the method described above.

<Weathering Resistance Evaluation Classifications>

Each test piece was held for 3.5 hours in a constant-temperature constant-humidity chamber at a temperature of 85° C. and a relative humidity of 85%. The appearance of the test pieces was then evaluated by eye under a fluorescent lamp. Weathering resistance was evaluated from the evaluation results using the following criteria.

S: Clouding and/or precipitates seen at the surface were extremely slight.

A: Clouding and/or precipitates seen at the surface were slight.

B: Strong clouding was seen at the surface and/or precipitates were generated.

C: Surface wetting that indicated deliquescence was observed, albeit to a low degree, and/or thick precipitates were produced.

D: Deliquescence occurred to an extent whereby clear sheet thickness reduction was not observed, and/or precipitates that covered the base glass were produced.

E: Deliquescence occurred to an extent whereby a clear sheet thickness reduction was observed, and/or precipitates were produced to such an extent that the base glass could not be seen.

TABLE 1 Example Comparative Example P₂O₅ L_(i2)O CuO Al₂O₃ Y₂O₃ La₂O₃ Gd₂O₃ Na₂O K₂O MgO CaO SrO BaO ZnO No (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) Example 1 61.36 10.15 26.31 1.45 0.50 0.22 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 2 59.16 10.34 26.80 1.48 0.00 0.00 0.00 0.00 0.00 2.22 0.00 0.00 0.00 0.00 Example 3 60.04 10.50 27.21 1.50 0.52 0.23 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 4 57.87 10.67 27.65 1.52 0.00 0.00 0.00 0.00 0.00 2.29 0.00 0.00 0.00 0.00 Example 5 58.76 10.83 28.08 1.55 0.54 0.23 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 6 57.56 11.15 28.90 1.60 0.55 0.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 7 56.61 10.99 28.48 1.57 0.00 0.00 0.00 0.00 0.00 2.35 0.00 0.00 0.00 0.00 Example 8 57.72 7.87 30.59 0.00 2.68 1.14 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 9 56.73 10.31 30.06 0.00 2.03 0.87 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 10 57.22 9.10 30.32 0.00 2.36 1.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 11 58.23 6.62 30.86 0.00 3.01 1.29 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 12 56.24 11.50 29.81 0.00 1.72 0.73 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 13 56.24 11.50 29.81 0.00 1.47 0.98 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 14 56.24 11.50 29.81 0.00 1.96 0.49 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 15 56.24 11.50 29.81 0.00 2.20 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 16 56.24 11.50 29.81 0.00 2.45 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 17 56.24 11.50 29.80 0.83 1.14 0.49 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 18 56.24 11.50 29.80 1.23 0.86 0.37 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 19 56.24 11.50 29.80 0.42 1.43 0.61 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 20 56.24 11.50 29.80 1.65 0.25 0.57 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 21 56.24 11.50 29.80 1.65 0.57 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 22 56.24 11.50 29.80 2.46 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 23 55.33 16.23 24.40 1.62 0.00 0.00 0.00 0.00 0.00 2.42 0.00 0.00 0.00 0.00 Example 24 55.33 11.31 29.32 1.62 0.00 0.00 0.00 0.00 0.00 2.42 0.00 0.00 0.00 0.00 Example 25 56.24 11.50 21.44 1.65 0.57 0.25 0.00 0.00 0.00 0.00 0.00 0.00 8.37 0.00 Example 26 56.24 11.50 22.48 1.65 0.57 0.25 0.00 0.00 0.00 0.00 0.00 0.00 7.33 0.00 Example 27 56.24 20.55 20.76 1.65 0.57 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 28 56.24 19.87 21.44 1.65 0.57 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 29 53.59 15.72 23.64 0.00 0.00 0.00 0.00 0.00 0.00 2.35 0.00 0.00 4.71 0.00 Example 30 53.59 15.72 23.64 0.00 0.00 0.00 0.00 0.00 0.00 4.70 0.00 0.00 2.35 0.00 Example 31 53.59 9.23 23.64 0.00 0.00 0.00 0.00 0.00 0.00 0.00 13.55 0.00 0.00 0.00 Example 32 53.59 9.23 23.64 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 13.55 0.00 0.00 Example 33 53.59 9.23 23.64 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 13.55 0.00 Example 34 56.35 9.71 31.37 2.57 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 35 54.44 15.97 24.01 0.80 0.00 0.00 0.00 0.00 0.00 4.78 0.00 0.00 0.00 0.00 Example 36 55.27 11.75 30.46 1.68 0.58 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 37 54.34 11.56 29.97 1.65 0.00 0.00 0.00 0.00 0.00 2.48 0.00 0.00 0.00 0.00 Example 38 57.72 10.56 25.97 5.65 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 39 54.63 10.09 32.61 2.67 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 40 54.17 12.04 31.21 1.73 0.60 0.26 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 41 53.19 12.30 31.88 1.76 0.61 0.26 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 42 55.89 16.92 21.29 5.90 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 43 55.89 22.72 15.49 5.90 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 44 52.07 8.48 26.70 2.25 0.00 0.00 0.00 2.56 5.11 0.83 0.00 0.00 1.64 0.37 Example 45 55.42 22.23 15.48 5.90 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.96 Example 46 52.18 12.56 32.56 1.80 0.62 0.27 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 47 52.89 23.50 16.37 6.24 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.02 Example 48 50.85 25.32 17.26 6.57 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 49 50.32 24.78 17.26 6.58 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 1.07 Example 50 51.36 5.60 26.83 1.48 0.00 0.00 0.00 4.28 8.57 0.54 0.00 0.00 1.08 0.25 Example 51 52.52 21.41 14.07 5.68 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 6.33 Example 52 49.60 19.99 13.70 5.31 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 11.40 Example 53 56.24 8.50 32.80 1.65 0.57 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 54 56.24 5.50 35.80 1.65 0.57 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 55 56.24 2.50 38.80 1.65 0.57 0.25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Example 56 53.66 15.03 14.16 3.98 0.00 0.00 0.00 2.71 5.42 1.46 0.00 0.00 2.92 0.66 Example 57 52.92 12.01 14.23 3.18 0.00 0.00 0.00 4.54 9.09 1.17 0.00 0.00 2.33 0.52 Example 58 52.18 8.95 14.31 2.37 0.00 0.00 0.00 6.40 12.79 0.87 0.00 0.00 1.74 0.39 Example 59 53.59 15.72 23.64 0.00 0.00 0.00 0.00 0.00 0.00 7.05 0.00 0.00 0.00 0.00 Example 60 53.59 9.23 23.64 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 13.55 Comp. Ex. X 50.67 2.76 14.45 0.73 0.00 0.00 0.00 10.15 20.30 0.27 0.00 0.00 0.54 0.12 Comp. Ex. A 53.59 19.30 27.11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Comp. Ex. B 53.59 12.73 33.68 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Comp. Ex. C 53.59 22.77 23.64 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Comp. Ex. D 36.07 23.63 9.87 3.32 0.00 0.00 0.00 0.00 10.45 2.74 5.31 1.99 6.61 0.00 Example 61 51.65 1.09 16.9 1.66 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 28.63 0.00 Example 62 51.16 1.10 16.2 1.50 0.44 0.20 0.00 0.00 0.00 0.00 0.00 0.00 29.40 0.00 Example 63 53.00 1.28 17.7 2.97 0.00 0.00 0.00 0.00 2.63 0.00 0.00 0.00 22.34 0.00 Example 64 51.16 1.16 20.7 1.50 0.44 0.20 0.00 0.00 0.00 0.00 0.00 0.00 24.85 0.00 Example 65 50.60 0.40 17.8 2.80 0.46 0.21 0.00 0.00 0.80 0.00 0.00 0.00 26.89 0.00 Example 66 50.79 0.40 17.82 1.53 0.99 0.46 0.00 0.00 0.78 0.00 0.00 0.00 27.19 0.00

TABLE 2 Example Molar Number of Total content Comparative molecular Specific Molar cations selected of oxides of O ion Example B₂O₃ SiO₂ Ta₂O₅ TiO₂ ZrO₂ Nb₂O₅ WO₃ Bi₂O₃ Cs₂O V₂O₅ Total weight gravity volume from main cation O/P main cations content No (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) M(g/mol) (g/cc) (cc/mol) group ratio (mo %) (anionic %) Example 1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 114.39 2.78 41.103 6 2.850 100.00 100.00 Example 2 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 110.79 2.78 39.823 5 2.870 100.00 100.00 Example 3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 113.45 2.80 40.517 6 2.870 100.00 100.00 Example 4 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 109.80 2.80 39.202 5 2.890 100.00 100.00 Example 5 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 112.54 2.82 39.908 6 2.890 100.00 100.00 Example 6 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 111.68 2.84 39.379 6 2.910 100.00 100.00 Example 7 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 108.84 2.82 38.583 5 2.911 100.00 100.00 Example 8 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 118.39 2.94 40.269 5 2.933 100.00 100.00 Example 9 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 114.93 2.91 39.537 5 2.933 100.00 100.00 Example 10 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 116.65 2.93 39.866 5 2.933 100.00 100.00 Example 11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 120.17 2.95 40.679 5 2.933 100.00 100.00 Example 12 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 113.25 2.89 39.132 5 2.933 100.00 100.00 Example 13 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 113.49 2.90 39.149 5 2.933 100.00 100.00 Example 14 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 113.01 2.89 39.117 5 2.933 100.00 100.00 Example 15 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 112.76 2.88 39.140 5 2.933 100.00 100.00 Example 16 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 112.51 2.88 39.122 4 2.933 100.00 100.00 Example 17 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 112.00 2.88 38.914 6 2.933 100.00 100.00 Example 18 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 111.38 2.87 38.843 6 2.933 100.00 100.00 Example 19 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 112.62 2.89 39.023 6 2.933 100.00 100.00 Example 20 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 111.06 2.87 38.697 6 2.933 100.00 100.00 Example 21 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 110.74 2.86 38.719 6 2.933 100.00 100.00 Example 22 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 109.48 2.84 38.522 4 2.933 100.00 100.00 Example 23 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 105.42 2.77 38.113 5 2.933 100.00 100.00 Example 24 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 107.86 2.84 38.020 5 2.933 100.00 100.00 Example 25 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 116.92 2.95 39.606 7 2.933 100.01 100.00 Example 26 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 116.15 2.94 39.484 7 2.933 100.01 100.00 Example 27 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 106.25 2.73 38.962 6 2.933 100.01 100.00 Example 28 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 103.59 2.74 38.957 6 2.933 100.01 100.00 Example 29 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 107.73 2.87 37.602 5 2.933 100.00 100.00 Example 30 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 105.07 2.81 37.378 5 2.933 100.00 100.00 Example 31 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 105.22 2.80 37.606 4 2.933 100.00 100.00 Example 32 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 111.68 2.98 37.446 4 2.933 100.00 100.00 Example 33 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 118.40 3.09 38.316 4 2.933 100.00 100.00 Example 34 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 110.46 2.87 38.448 4 2.933 100.00 100.00 Example 35 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 103.89 2.76 37.601 5 2.933 100.00 100.00 Example 36 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 110.05 2.87 38.305 6 2.950 100.00 100.00 Example 37 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 107.11 2.85 37.530 5 2.951 100.00 100.00 Example 38 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 111.54 2.83 39.440 4 2.964 100.00 100.00 Example 39 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 109.22 2.90 37.677 4 2.964 100.00 100.00 Example 40 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 109.27 2.90 37.730 6 2.971 100.00 100.00 Example 41 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 108.56 2.91 37.256 6 2.990 100.00 100.00 Example 42 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 107.34 2.77 38.794 4 3.000 100.00 100.00 Example 43 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 104.48 2.68 38.935 4 3.000 100.00 100.00 Example 44 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 109.52 2.88 38.095 9 3.004 100.00 100.00 Example 45 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 104.43 2.70 38.676 5 3.009 100.00 100.00 Example 46 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 107.85 2.94 36.745 6 3.010 100.00 100.00 Example 47 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 102.29 2.73 37.484 5 3.063 100.00 100.00 Example 48 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 100.17 2.74 36.560 4 3.113 100.00 100.00 Example 49 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 100.13 2.76 36.253 5 3.124 100.00 100.00 Example 50 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 110.24 2.85 38.695 9 3.002 100 100.00 Example 51 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 103.07 2.76 37.414 5 3.060 100 100.00 Example 52 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 101.97 2.83 36.019 5 3.115 100 100.00 Example 53 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 112.23 2.93 38.290 6 2.933 100.00 100.00 Example 54 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 113.72 2.95 38.509 6 2.933 100.00 100.00 Example 55 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 115.21 2.97 38.751 6 2.933 100.00 100.00 Example 56 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 108.37 2.75 39.421 9 3.006 100.00 100.00 Example 57 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 109.12 2.73 40.046 9 3.005 100 100.00 Example 58 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 109.89 2.70 40.670 9 3.004 100 100.00 Example 59 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 102.41 2.76 37.091 4 2.933 100.00 100.00 Example 60 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 108.85 2.90 37.505 4 2.933 100.00 100.00 Comp. Ex. X 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 111.44 2.66 41.958 9 3.001 100 100.00 Comp. Ex. A 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 103.40 2.79 37.113 3 2.933 100 100.00 Comp. Ex. B 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 106.66 2.89 36.882 3 2.933 100 100.00 Comp. Ex. C 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 101.67 2.73 37.243 3 2.933 100 100.00 Comp. Ex. D 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100 95.62 2.95 32.413 9 3.478 99.99 100.00 Example 61 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.0 132.70 3.40 39.03 5 3.00 100 100.00 Example 62 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.0 134.08 3.42 39.24 7 3.02 100 100.00 Example 63 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.0 129.49 3.25 39.84 6 3.00 100 100.00 Example 64 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.0 130.67 3.39 38.55 7 3.02 100 100.00 Example 65 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.0 132.70 3.30 39.14 8 3.06 100 100.00 Example 66 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 100.0 134.10 3.43 39.10 8 3.04 100 100.00

TABLE 3 Example Comparative A₁ = A₂ = α₁ = α₂ = Example MgO + Al₂O₃ (Na₂O + K₂O + O(P) − (O(P) − (O(P) − C 70400 × 76522 × C − 3200 × C − 3478 × No (mol %) ZnO)/Li₂) O(P) O(others) O(others) O(others)) × Cu O(others)) × C (mmol/cc) exp(−2.855 × R) exp(−2.855 × R) exp(−2.278 × R) exp(−2.278 × R) Example 1 1.45 0.00 306.788 42.994 263.794 6941.68 1688.85 6.40 20.58 22.37 1.5

1.14 Example 2 3.69 0.00 295.806 43.795 252.011 6754.81 1690.23 6.73 19.45 21.14 2.10 1.70 Example 3 1.50 0.00 300.182 44.464 255.718 6

9.24 1717.61 6.72 19.44 21.13 2.09 1.69 Example 4 3.81 0.00 289.362 45.177 244.185 6751.70 1722.29 7.05 18.3

19.9

2.53 2.25 Example 5 1.55 0.00 293.822 45.880 247.942 6962.41 1744.62 7.04 18.3

19.95 2.61 2.23 Example 6 1.60 0.00 287.781 47.224 240.557 69

2.94 1765.65 7.34 17.34 18.85 3.11 2.75 Example 7 3.92 0.00 283.059 46.529 238.530 6735.74 1745.78 7.38 17.31 18.81 3.1

2.79 Example 8 0.00 0.00 288.584 49.934 238.650 729

.89 1812.77 7.60 16.27 17.6

3.58 3.23 Example 9 0.00 0.00 283.629 49.077 234.552 7051.38 1783.51 7.80 16.27 17.69 3.59 3.24 Example 10 0.00 0.00 286.085 49.502 236.583 7174.03 1799.55 7.61 16.27 17.68 3.59 3.24 Example 11 0.00 0.00 291.127 50.274 240.752 742

.10 1826.28 2.59 16.27 17.69 3.57 3.22 Example 12 0.00 0.00 281.214 48.660 232.554 6931.77 1771.40 7.82 16.27 17.69 3.60 3.2

Example 13 0.00 0.00 281.214 48.660 232.554 8931.77 1770.60 7.61 16.27 17.69 3.60 3.2

Example 14 0.00 0.00 281.214 48.860 232.354 6931.77 1772.07 7.62 16.27 17.69 3.60 3.2

Example 15 0.00 0.00 281.214 48.660 232.354 6931.77 1771.03 7.62 16.27 17.69 3.60 3.25 Example 16 0.00 0.00 281.214 48.660 232.554 6931.77 1771.83 7.62 16.27 17.69 3.60 3.25 Example 17 0.

3 0.00 281.190 48.681 232.509 6929.83 1780.78 7.66 16.26 17.67 3.

4 3.30 Example 18 1.23 0.00 281.190 49.681 232.509 6928.83 1784.07 7.67 16.26 17.67 3.66 3.31 Example 19 0.42 0.00 281.190 48.681 232.509 6929.89 1775.82 7.64 16.26 17.67 3.62 3.27 Example 20 1.65 0.00 281.176 48.694 232.482 6928.69 1790.50 7.70 16.25 17.67 3.69

.

4 Example 21 1.65 0.00 281.176 48.694 232.482 6928.89 1789.47 7.70 16.25 17.67 3.68 3.3

Example 22 2.40 0.00 281.176 48.694 232.482 6928.69 1798.6

7.74 16.2

17.67 3.72 3.37 Example 23 4.04 0.00 276.631 47.908 298.724 5581.61 1464.50 6.40 16.25 17.67 2.39 2.04 Example 24 4.04 0.00 276.631 47.908 228.724 6706.50 1763.95 7.71 16.25 17.67 3.70 3.35 Example 25 1.65 0.00 281.176 48.700 232.475 4984.27 1258.45 5.41 16.25 17.67 1.40 1.05 Example 26 1.65 0.00 281.176 48.700 232.475 5226.04 1323.27 5.69 16.25 17.67 1.68 1.33 Example 27 1.65 0.00 281.176 48.703 232.473 4826.13 123

.69 5.03 16.25 17.66 1.32 0.97 Example 28 1.65 0.00 281.176 48.703 237.473 4984.21 1279.42 5.50 16.25 17.66 1.49 1.14 Example 29 2.3

0.00 267.043 46.411 221.532 5236.32 1392.58 6.29 16.25 17.66 2.27 1.92 Example 30 4.70 0.00 267.943 46.411 221.532 5236.32 1400.92 6.32 16.25 17.66 2.31 1.86 Example 31 0.00 0.00 267.941 48.412 221.529 5236.22 1392.38 6.29 16.25 17.

2.27 1.92 Example 32 0.00 0.00 267.941 48.412 221.529 5236.22 1398.36 6.31 16.25 17.6

2.30 1.95 Example 33 0.00 0.00 267.941 46.412 221.529 5236.22 1386.59 6.17 16.25 17.66 2.1

1.81 Example 34 2.57 0.00 281.732 48.803 232.929 7307.34 1800.57

.18 16.25 17.66 4.15 3.80 Example 35 5.58 0.00 272.206 47.158 225.048 5404.06 1437.23 6.39 16.25 17.66 2.37 2.03 Example 36 1.68 0.00 276.361 49.765 226.496 6901.85 1

01.82 7.95 15.47 16.82 4.09 3.76 Example 37 4.13 0.00 271.708 48.963 222.745 6675.06 1778.59 7.98 15.46 16.80 4.1

3.79 Example 38 5.65 0.00 788.611 53.583 235.027 6102.88 1547.37

.88 14.87 16.16 2.85 2.52 Example 39 2.67 0.00 273.160 50.715 222.445 7253.18 1925.11

.

14.87 16.16 4.92 4.

9 Example 40 1.73 0.00 270.861 50.989 219.872 6861.75 1818.05 8.27 14.60 15.87 4.59 4.27 Example 41 1.76 0.00 265.938 52.084 213.854. 6817.32 1829.86 8.56 13.83 15.03 5.03 4.72 Example 42 5.90 0.00 279.470 55.902 223.567 4759.86 1226.95

.49 13.42 14.59 2.04 1.74 Example 43 5.90 0.00 279.470 55.902 223.567 3482.51 8

9.32 3.98 13.42 14.59 0.53 0.23 Example 44 3.07 0.95 260.326 52.432 207.094 5550.91 1457.13 7.01 13.29 14.44 3.59 3.29 Example 45 5.90 0.04 277.099 56.381 220.717 3417.79 883.68 4.00 13.0

14.23 0.83 0.33 Example 46 1.80 0.00 260.911 53.203 207.708 6783.62 1840.69 8.88 13.0

14.19 5.49 5.20 Example 47 6.24 0.04 264.423 59.587 204.941 3352.26

94.33 4.37 11.20 12.18 1.38 1.12 Example 48 6.57 0.00 254.242 62.297 191.945 3312.83 906.14 4.72 9.73 10.58 2.06 1.82 Example 49 6.58 0.04 251.589 62.834 186.758 3257.30 898.50 4.76 9.41 10.73 2.17 1.94 Example 50 2.03 2.340 256.801 51.606 205.185 5505.96 1422.93 6.93 13.3

17.48 3.

1 3.21 Example 51 5.60 0.296 262.581 58.844 203.746 2065.91 766.00

3.76 11.30 12.2

0.76 0.50 Example 52 5.31 0.570 248.020 61.007 187.013 2

1.40 711.130 3.80 9.67 10.51 1.15 0.92 Example 53 1.85 0.00 281.176 48.694 232.482 7628.14 1991.7

2 8.57 1

.25 17.67 4.

4.20 Example 54 1.65 0.00 281.176 48.694 232.482 6323.59 2161.474 9.30 1

.25 17.67 5.28 4.9

Example 55 1.65 0.00 281.176 48.694 232.482 9021.03 2327.952 10.01 1

.25 17.67 6.00 5.65 Example 56 5.44 0.585 268.282 54.313 213.989 3029.4

28

.50 3.59 13.19 14.34 0.10 −0.10 Example 57 4.35 1.179 264.610 53.447 211.103 3005.00 750.39 3.55 13.23 14.39 0.15 −0.15 Example 58 3.24 2.1

7 260.892 52.570 208.322 2

0.18 732.77

.52 13.2

14.43 0.101

−0.20 Example 59 7.05 0.00 267.943 46.411 221.532 5236.32 1411.74 6.37 16.25 17.66 2.3

2.01 Example 60 0.00 1.47 267.941 46.412 221.529 5236.22 1398.15 6.30 18.25 17.

2.29 1.

4 Comp. Ex. X 1.00 11.073 253.360 50.793 202.567 2927.50 697.72 3.44 13.3

14.54 0.009 −0.29 Comp. Ex. A 0.00 0.000 267.943 46.411 221.532 6005.22 7.30 16.25 17.6

3.29 2.94 Comp. Ex. B 0.00 0.000 267.943 46.411 221.532 7461.38 9.13 16.25 17.6

5.12 4.77 Comp. Ex. C 0.00 0.000 267.943 46.411 221.532 6735.32

.

5 16.25 17.6

2.33 1.

Comp. Ex. D 6.06 0.44 180.350 70.560 109.790 1083.63 3.05 3.42

.73 1.89 1.78 Example 61 1.45 0.00 258.228 51.64 206.59 3498.49 896.34 4.34 13.42 14.59 0.834 0.595 Example 62 1.48 0.00 255.780 53.08 202.70 3275.81 8

4.73 4.12 12.68 13.78 0.827 0.541 Example 63 1.50 2.06 265.000 52.91 212.09 3162.01 944.35 4.45 13.42 14.59 1.008 0.708 Example 64 1.52 0.00 255.883 53.08 202.72 4188.47 10

6.61 5.3

12.68 13.78 2.061 1.774 Example 65 1.

5 1.98 252.999 56.34 196.6

3509.55 890.57 4.5

11.47 12.47 1.520 1.2

Example 66 1.

1.96 253.970 55.13 1

.

4 3542.58 906.1

4.5

11.87 12.90 1.433 1.162

indicates data missing or illegible when filed

TABLE 4 (3 × Al₂O₃ + Al₂O₂ + (3 × Al₂O₃ + Y₂O₃ + La₂O₃ + O ion Example P₂O₅ + Li₂O + Na₂O + Y₂O₃ + Y₂O₃ + La₂O₃ + Gd₂O₃ + BaO/3 + (Coefficient of Comparative B₂O₃ + Li₂O + Na₂O + Na₂O + K₂O + CaO + La₂O₃ + Gd₂O₃ + BaO/3 + (CaO + SrO)/6)/ oxide × molar Example SiO₂ CuO K₂O K₂O SrO + BaO Gd₂O₃ (CaO + SrO)/6) (P₂O₅ + Li₂O + percentage No (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) (mol %) CuO) of cation) Example 1 0.00 97.82 10.15 0.00 0.00 2.18 5.09 0.052 349.78 Example 2 0.00 96.31 10.34 0.00 0.00 1.48 4.43 0.046 339.60 Example 3 0.00 97.75 10.50 0.00 0.00 2.25 5.26 0.054 344.65 Example 4 0.00 96.19 10.67 0.00 0.00 1.52 4.57 0.048 334.54 Example 5 0.00 97.68 10.83 0.00 0.00 2.32 5.43 0.056 339.70 Example 6 0.00 97.61 11.15 0.00 0.00 2.39 5.59 0.057 335.00 Example 7 0.00 98.08 10.99 0.00 0.00 1.57 4.71 0.049 329.59 Example 8 0.00 96.17 7.87 0.00 0.00 3.83 3.83 0.040 338.52 Example 9 0.00 97.10 10.31 0.00 0.00 2.90 2.90 0.030 332.71 Example 10 0.00 96.64 9.10 0.00 0.00 3.36 3.36 0.035 335.59 Example 11 0.00 95.70 6.62 0.00 0.00 4.30 4.30 0.045 341.50 Example 12 0.00 97.55 11.50 0.00 0.00 2.45 2.45 0.025 329.87 Example 13 0.00 97.55 11.50 0.00 0.00 2.45 2.45 0.025 329.87 Example 14 0.00 97.55 11.50 0.00 0.00 2.45 2.45 0.025 329.87 Example 15 0.00 97.55 11.50 0.00 0.00 2.45 2.45 0.025 329.87 Example 16 0.00 97.55 11.50 0.00 0.00 2.45 2.45 0.025 329.87 Example 17 0.00 97.54 11.50 0.00 0.00 2.46 4.11 0.042 329.87 Example 18 0.00 97.54 11.50 0.00 0.00 2.46 4.93 0.051 329.87 Example 19 0.00 97.54 11.50 0.00 0.00 2.46 3.29 0.034 329.87 Example 20 0.00 97.54 11.50 0.00 0.00 2.46 5.76 0.059 329.87 Example 21 0.00 97.54 11.50 0.00 0.00 2.46 5.76 0.059 329.87 Example 22 0.00 97.54 11.50 0.00 0.00 2.46 7.39 0.076 329.87 Example 23 0.00 95.96 16.23 0.00 0.00 1.62 4.85 0.051 324.54 Example 24 0.00 95.96 11.31 0.00 0.00 1.62 4.85 0.051 324.54 Example 25 0.00 89.17 11.50 0.00 8.37 2.46 8.55 0.096 329.88 Example 26 0.00 90.21 11.50 0.00 7.33 2.46 8.20 0.091 329.88 Example 27 0.00 97.55 20.55 0.00 0.00 2.46 5.76 0.059 329.88 Example 28 0.00 97.55 19.87 0.00 0.00 2.46 5.76 0.059 329.88 Example 29 0.00 92.95 15.72 0.00 4.71 0.00 1.57 0.017 314.35 Example 30 0.00 92.95 15.72 0.00 2.35 0.00 0.78 0.008 314.35 Example 31 0.00 86.45 9.23 0.00 13.55 0.00 2.26 0.026 314.35 Example 32 0.00 86.45 9.23 0.00 13.55 0.00 2.26 0.026 314.35 Example 33 0.00 86.45 9.23 0.00 13.55 0.00 4.52 0.052 314.35 Example 34 0.00 97.43 9.71 0.00 0.00 2.57 7.72 0.079 330.53 Example 35 0.00 94.42 15.97 0.00 0.00 0.80 2.40 0.025 319.38 Example 36 0.00 97.48 11.75 0.00 0.00 2.52 5.89 0.060 326.13 Example 37 0.00 95.87 11.66 0.00 0.00 1.65 4.96 0.052 320.67 Example 38 0.00 94.35 10.68 0.00 0.00 5.65 16.96 0.180 342.19 Example 39 0.00 97.33 10.09 0.00 0.00 2.67 8.02 0.082 323.88 Example 40 0.00 97.42 12.04 0.00 0.00 2.58 6.03 0.062 321.85 Example 41 0.00 97.36 12.30 0.00 0.00 2.64 6.16 0.063 318.02 Example 42 0.00 94.10 16.92 0.00 0.00 5.90 17.69 0.188 335.37 Example 43 0.00 94.10 22.72 0.00 0.00 5.90 17.68 0.188 335.37 Example 44 0.00 87.24 16.15 7.67 9.32 2.25 7.29 0.084 312.78 Example 45 0.00 93.14 22.23 0.00 0.00 5.90 17.70 0.190 333.48 Example 46 0.00 97.31 12.56 0.00 0.00 2.69 6.29 0.065 314.11 Example 47 0.00 92.75 23.50 0.00 0.00 6.24 18.71 0.202 324.01 Example 48 0.00 93.43 25.32 0.00 0.00 6.57 19.72 0.211 316.54 Example 49 0.00 92.35 24.78 0.00 0.00 6.58 19.73 0.214 314.42 Example 50 0.00 83.79 18.45 12.85 13.94 1.48 4.81 0.057 308.41 Example 51 0.00 87.99 21.41 0.00 0.00 5.68 17.04 0.194 321.43 Example 52 0.00 83.29 19.99 0.00 0.00 5.31 15.92 0.191 309.03 Example 53 0.00 97.54 8.50 0.00 0.00 2.46 5.76 0.059 329.87 Example 54 0.00 97.54 5.50 0.00 0.00 2.46 5.76 0.059 329.87 Example 55 0.00 97.54 2.50 0.00 0.00 2.46 5.76 0.059 329.87 Example 56 0.00 82.84 23.16 8.14 11.06 3.98 12.93 0.156 322.60 Example 57 0.00 79.16 25.64 13.63 15.98 3.18 10.33 0.131 318.06 Example 58 0.00 75.44 28.14 19.19 20.93 2.37 7.70 0.102 313.46 Example 59 0.00 92.95 15.72 0.00 0.00 0.00 0.00 0.000 314.35 Example 60 0.00 86.45 9.23 0.00 0.00 0.00 0.00 0.000 314.35 Comp. Ex. X 0.00 87.89 33.22 30.45 30.99 0.73 2.38 0.035 304.15 Comp. Ex. A 0.00 100.00 19.30 0.00 0.00 0.00 0.00 0.000 314.35 Comp. Ex. B 0.00 100.00 12.73 0.00 0.00 0.00 0.00 0.000 314.35 Comp. Ex. C 0.00 100.00 22.77 0.00 0.00 0.00 0.00 0.000 314.35 Comp. Ex. D 0.00 69.57 34.08 10.45 24.36 3.32 13.38 0.192 250.91 Example 61 0.00 69.67 1.09 0.00 28.63 1.66 14.53 0.209 309.87 Example 62 0.00 68.42 1.10 0.00 29.40 2.14 14.93 0.218 308.86 Example 63 0.00 72.02 3.91 2.63 24.97 2.97 16.37 0.227 317.91 Example 64 0.00 72.98 1.16 0.00 24.85 2.14 13.42 0.184 308.88 Example 65 0.00 68.85 1.20 0.80 27.69 3.47 18.03 0.262 309.34 Example 66 0.00 69.01 1.18 0.78 27.97 2.98 15.11 0.219 309.10

TABLE 5 Example Transmittance @ λ T50 = 645 nm Transmittance @ λ T50 = 633 nm Comparative Sheet Ave. Sheet Ave. Example thickness T1200 T1100-800 T750 T600 T400 thickness T1200 T1100-800 T750 T600 T400 No (mm) (%) (%) (%) (%) (%) (mm) (%) (%) (%) (%) (%) Example 1 0.170 2.420 0.386 4.049 75.895 85.936 0.225 0.751 0.071 1.483 71.402 84.147 Example 2 0.153 3.585 1.204 4.379 76.550 87.133 0.203 1.241 0.297 1.619 72.148 85.676 Example 3 0.151 3.304 0.637 4.417 76.165 86.742 0.200 1.130 0.134 1.660 71.725 85.187 Example 4 0.136 4.965 1.520 4.856 76.366 86.849 0.180 1.935 0.410 1.379 71.971 85.323 Example 5 0.138 4.423 0.915 4.817 76.262 86.684 0.182 1.673 0.216 1.873 71.874 85.121 Example 6 0.117 6.096 1.176 5.454 75.642 85.667 0.153 2.810 0.316 2.255 71.209 83.849 Example 7 0.120 6.150 1.639 5.209 76.483 86.596 0.159 2.578 0.459 2.071 72.136 85.002 Example 8 0.099 10.009 3.639 6.913 75.589 86.127 0.129 5.181 1.391 3.167 71.295 84.500 Example 9 0.105 9.073 3.852 6.382 75.878 86.330 0.137 4.449 1.474 2.808 71.568 84.728 Example 10 0.103 9.130 3.065 6.520 75.821 86.198 0.134 4.514 1.098 2.909 71.534 84.572 Example 11 0.093 10.940 3.725 7.342 75.600 86.153 0.121 5.795 1.447 3.452 71.352 84.550 Example 12 0.110 7.889 2.030 5.618 76.300 86.133 0.145 3.614 0.614 2.310 71.954 84.421 Example 13 0.103 8.303 2.000 5.850 75.822 86.018 0.135 3.940 0.624 2.490 71.467 84.314 Example 14 0.105 7.935 1.805 5.707 75.906 85.851 0.137 3.713 0.551 2.411 71.572 84.101 Example 15 0.110 7.829 2.111 5.651 75.926 86.081 0.145 3.644 0.673 2.377 71.591 84.393 Example 16 0.110 7.829 1.868 5.713 75.952 85.683 0.144 3.630 0.569 2.401 71.601 83.873 Example 17 0.109 7.545 2.461 5.570 76.229 85.959 0.143 3.427 0.798 2.299 71.896 84.208 Example 18 0.107 8.279 3.704 5.792 75.944 85.808 0.141 3.909 1.379 2.446 71.595 84.036 Example 19 0.111 7.955 2.039 5.741 75.769 85.493 0.145 3.730 0.641 2.433 71.409 83.644 Example 20 0.109 7.575 1.719 5.696 75.771 85.549 0.143 3.492 0.517 2.404 71.402 83.712 Example 21 0.111 7.517 2.820 5.485 76.196 86.037 0.146 3.417 0.967 2.258 71.865 84.313 Example 22 0.113 6.912 2.245 5.466 26.144 85.839 0.149 3.065 0.720 2.252 71.810 84.061 Example 23 0.136 6.235 1.524 4.997 76.331 86.869 0.180 2.616 0.418 1.952 71.928 85.350 Example 24 0.109 7.924 2.518 5.792 76.198 86.051 0.143 3.648 0.821 2.414 71.847 84.335 Example 25 0.166 5.967 1.064 4.555 76.384 86.422 0.220 2.453 0.263 1.715 71.964 84.758 Example 26 0.164 6.131 1.032 4.644 76.229 86.462 0.216 2.571 0.259 1.782 71.826 84.831 Example 27 0.178 5.716 0.962 4.490 76.476 87.041 0.237 2.297 0.227 1.667 72.040 85.550 Example 28 0.166 5.871 0.952 4.567 76.344 86.795 0.220 2.383 0.226 1.707 71.878 85.230 Example 29 0.147 5.614 1.100 4.346 76.437 85.084 0.194 2.269 0.272 1.616 72.043 83.418 Example 30 0.141 6.138 1.191 4.708 76.434 86.083 0.187 2.562 0.306 1.804 72.057 84.330 Example 31 0.115 9.231 2.024 5.862 76.000 85.046 0.150 4.511 0.637 2.486 71.667 83.059 Example 32 0.118 8.642 1.911 5.389 75.947 83.451 0.155 4.099 0.584 2.202 71.548 80.992 Example 33 0.136 5.811 1.076 4.490 76.070 83.894 0.179 2.427 0.275 1.729 71.692 81.553 Example 34 0.095 8.422 3.869 6.327 75.500 78.928 0.123 4.090 1.514 2.818 71.178 75.416 Example 35 0.136 6.639 1.539 5.002 76.248 86.637 0.179 2.873 0.429 1.978 71.879 85.068 Example 36 0.098 9.186 2.418 6.354 75.858 85.818 0.127 4.546 0.813 2.810 71.575 84.084 Example 37 0.097 9.903 4.813 6.222 76.007 85.574 0.127 4.987 1.962 2.715 71.725 83.758 Example 38 0.089 13.671 4.955 8.284 74.773 79.147 0.115 7.946 2.187 4.174 70.538 75.884 Example 39 0.081 9.477 4.338 7.011 75.279 76.917 0.106 4.820 1.770 3.260 70.972 72.983 Example 40 0.093 10.613 2.829 6.630 75.612 84.696 0.121 5.535 1.008 2.987 71.303 82.686 Example 41 0.084 12.120 3.114 7.023 75.307 83.566 0.110 6.612 1.165 3.254 70.984 81.262 Example 42 0.123 12.199 2.875 7.632 75.001 81.159 0.159 6.780 1.088 3.700 70.728 78.313 Example 43 0.179 11.035 2.416 6.870 75.418 83.778 0.233 5.861 0.844 3.167 71.128 81.535 Example 44 0.121 5.836 1.463 4.971 75.636 83.755 0.158 2.483 0.418 2.013 71.239 81.421 Example 45 0.162 12.775 2.829 7.269 75.394 85.975 0.209 7.126 1.050 3.431 71.138 84.337 Example 46 0.077 13.453 3.829 7.299 75.463 82.431 0.100 7.596 1.520 3.435 71.199 79.845 Example 47 0.129 18.122 4.807 8.623 74.666 82.277 0.166 11.384 2.126 4.379 70.385 79.748 Example 48 0.108 21.057 6.228 9.481 74.244 76.092 0.138 14.069 3.048 5.091 70.061 72.289 Example 49 0.103 22.85 6.562 9.845 74.25  82.32 0.132 15.563 3.278 5.313 70.039 79.896 Example 50 0.142 3.235 1.070 3.535 76.009 82.607 0.188 1.088 0.280 1.224 71.490 79.832 Example 51 0.148 20.133 5.334 8.706 74.637 82.687 0.190 13.131 2.486 4.484 70.420 80.300 Example 52 0.130 24.979 6.961 9.278 74.584 80.034 0.167 17.341 3.486 4.979 70.375 77.026 Example 53 0.083 10.259 6.783 75.366 85.528 0.108 5.336 2.408 3.119 71.071 83.757 Example 54 0.077 10.318 7.232 75.154 85.485 0.100 5.410 2.270 3.414 70.853 83.719 Example 55 0.067 11.519 7.812 74.967 85.190 0.087 6.304 4.105 3.819 70.694 83.375 Example 56 0.232 6.624 1.108 4.899 75.666 82.733 0.304 2.925 0.295 1.969 71.265 80.314 Example 57 0.271 4.010 0.540 3.549 76.269 81.762 0.359 1.441 0.108 1.225 71.798 78.739 Example 58 0.315 2.547 0.268 2.575 76.479 79.774 0.421 0.766 0.041 0.777 71.951 76.121 Example 59 0.136 7.005 1.547 6.102 76.193 86.207 0.179 3.076 0.432 2.024 71.797 84.506 Example 60 0.123 9.383 2.532 5.946 76.147 86.607 0.162 4.617 0.847 2.539 71.859 85.069 Comp. Ex. X 0.352 1.846 0.156 2.059 73.631 69.056 0.463 0.538 0.023 0.621 68.694 63.135 Comp. Ex. A 0.125 5.963 2.057 4.579 76.344 81.915 0.166 2.459 0.610 1.733 71.929 76.960 Comp. Ex. B 0.091 7.734 4.856 5.651 75.965 83.367 0.119 3.561 1.965 2.368 71.619 80.912 Comp. Ex. C 0.147 5.181 0.938 4.201 76.536 85.249 0.196 2.010 0.217 1.521 72.100 83.212 Comp. Ex. D 0.089 36.027 13.809 13.887 72.114 87.082 0.111 28.827 8.950 8.852 68.090 86.005 Example 61 0.160 9.22 1.689 5.851 75.040 86.070 0.209 4.578 0.536 2.527 70.664 84.520 Example 62 0.165 11.38 2.359 6.472 74.730 86.550 0.214 6.136 0.837 2.950 70.410 85.180 Example 63 0.160 8.30 1.562 5.826 74.868 86.022 0.210 4.009 0.482 2.527 70.485 84.474 Example 64 0.120 11.00 2.498 6.542 74.889 86.311 0.156 5.850 0.879 2.977 70.580 84.867 Example 65 0.119 13.52 2.865 7.513 74.388 83.546 0.154 7.806 1.158 3.662 70.124 81.432 Example 66 0.127 12.87 2.981 7.126 74.576 85.270 0.164 7.230 1.159 3.363 70.256 83.564

TABLE 6 Example Comparative Transmittance@ Sheet thickness 0.11 mm Transmittance@ Sheet thickness 0.21 mm Example λ T50 T1200 Ave. T1100-800 T750 T600 T400 λ T50 T1200 Ave. T1100-800 T750 T600 T400 No (nm) (%) (%) (%) (%) (%) (nm) (%) (%) (%) (%) (%) Example 1 666 8.785 2.590 12.245 81.175 87.953 636 1.041 0.113 1.963 72.627 84.642 Example 2 660 8.882 4.008 10.259 80.528 88.400 632 1.063 0.243 1.400 71.526 85.465 Example 3 660 8.168 2.414 10.090 80.124 88.077 631 0.906 0.097 1.356 70.842 84.870 Example 4 655 8.624 3.285 8.471 79.065 87.755 627 1.005 0.165 0.973 69.066 84.279 Example 5 655 8.150 2.287 8.725 79.157 87.681 627 0.902 0.087 1.028 69.219 84.143 Example 6 648 7.112 1.496 6.403 76.476 86.001 620 0.696 0.042 0.569 64.812 81.093 Example 7 649 7.775 2.313 6.682 77.700 87.031 622 0.825 0.088 0.618 66.807 82.956 Example 8 640 7.953 2.581 5.232 74.028 85.543 614 0.861 0.107 0.387 60.908 80.269 Example 9 643 8.149 3.332 5.639 75.212 86.087 616 0.902 0.176 0.447 62.782 81.246 Example 10 642 7.788 2.429 5.434 74.831 85.828 615 0.827 0.094 0.416 62.176 80.780 Example 11 637 7.494 2.120 4.685 73.042 85.195 611 0.769 0.074 0.314 59.359 79.648 Example 12 645 7.939 2.049 5.659 76.336 86.147 619 0.858 0.059 0.450 64.586 81.356 Example 13 642 7.045 1.546 4.846 74.839 85.639 616 0.683 0.042 0.334 62.190 80.442 Example 14 643 7.046 1.498 4.987 75.210 85.575 616 0.683 0.041 0.353 62.780 30.326 Example 15 645 7.910 2.144 5.717 75.986 86.104 618 0.852 0.079 0.459 64.022 81.277 Example 16 645 7.830 1.868 5.715 75.953 85.683 618 0.836 0.061 0.458 63.969 80.521 Example 17 644 7.310 2.352 5.376 76.051 85.888 618 0.733 0.090 0.408 64.126 80.889 Example 18 644 7.823 3.437 5.427 75.607 85.673 617 0.834 0.184 0.415 63.413 80.503 Example 19 645 8.056 2.078 5.823 75.844 85.524 618 0.882 0.073 0.475 63.793 80.235 Example 20 645 7.466 1.681 5.605 75.687 85.514 618 0.763 0.051 0.442 63.541 80.218 Example 21 645 7.672 2.900 5.613 76.311 86.082 619 0.804 0.140 0.443 64.546 81.238 Example 22 646 7.439 2.490 5.922 76.549 86.001 619 0.758 0.105 0.490 64.930 81.093 Example 23 655 10.451 3.312 8.739 79.076 87.785 627 1.450 0.175 1.031 69.083 84.333 Example 24 644 7.661 2.397 5.575 76.004 85.985 618 0.802 0.094 0.437 64.050 81.063 Example 25 665 15.063 4.679 12.600 81.277 88.190 635 2.914 0.344 2.073 72.800 85.078 Example 26 664 14.883 4.347 12.347 81.002 88.159 634 2.848 0.304 1.994 72.331 85.021 Example 27 668 16.528 5.335 14.240 81.991 88.812 638 3.480 0.437 2.618 74.027 86.226 Example 28 664 14.767 4.268 12.497 81.200 88.425 635 2.806 0.293 2.040 72.668 85.512 Example 29 658 11.294 3.272 9.321 80.009 86.933 630 1.682 0.172 1.166 70.648 82.778 Example 30 657 11.167 3.056 9.084 79.586 87.305 628 1.646 0.155 1.110 69.936 83.455 Example 31 647 10.114 2.348 6.539 76.571 85.303 620 1.362 0.095 0.593 64.966 79.840 Example 32 648 10.083 2.447 6.485 76.890 83.969 621 1.355 0.103 0.583 65.483 77.474 Example 33 655 9.893 2.495 8.034 78.869 85.354 627 1.306 0.106 0.878 68.738 79.931 Example 34 638 5.725 2.341 4.106 73.159 77.032 612 0.460 0.093 0.244 59.551 65.714 Example 35 655 10.915 3.305 8.676 78.966 87.581 627 1.576 0.173 1.017 68.900 83.961 Example 36 639 6.865 1.538 4.532 74.054 85.095 614 0.650 0.042 0.294 60.950 79.469 Example 37 639 7.293 3.223 4.298 74.066 84.760 613 0.730 0.163 0.266 60.869 78.872 Example 38 635 8.768 2.535 4.727 71.289 76.466 608 1.037 0.107 0.319 56.679 64.796 Example 39 631 4.267 1.507 2.839 30.222 72.295 606 0.262 0.040 0.121 55.070 58.216 Example 40 637 7.065 7.488 4.039 72.903 83.428 611 0.687 0.040 0.236 59.155 76.524 Example 41 633 6.534 1.142 3.205 70.902 81.217 607 0.592 0.020 0.152 56.093 72.699 Example 42 650 15.078 4.098 9.910 76.805 82.211 621 2.920 0.277 1.310 65.021 74.406 Example 43 673 24.969 9.615 18.661 81.337 86.764 637 7.649 1.312 4.387 72.803 82.472 Example 44 649 7.453 2.101 6.439 76.943 84.435 621 0.761 0.074 0.575 65.570 78.296 Example 45 665 23.974 8.407 16.332 80.271 87.777 633 7.078 1.038 3.401 71.090 84.318 Example 46 629 5.874 1.006 2.448 69.361 78.709 604 0.483 0.020 0.091 53.789 68.472 Example 47 653 23.071 7.382 12.262 76.991 83.622 623 6.577 0.825 1.965 65.648 76.863 Example 48 644 20.512 5.944 9.106 73.965 75.838 615 5.255 0.555 1.115 60.810 63.784 Example 49 642 20.83 5.541 8.481 73.21 81.73 613 5.409 0.519 0.974 59.636 73.579 Example 50 657 6.896 2.888 7.386 79.315 84.591 629 0.656 0.135 0.748 69.482 78.574 Example 51 661 29.812 10.965 16.017 78.732 84.942 629 10.730 1.721 3.277 68.511 79.197 Example 52 654 30.593 10.283 13.259 77.030 81.755 623 11.272 1.568 2.285 65.712 73.621 Example 53 632 5.085 2.266 2.944 70.763 83.627 607 0.367 0.087 0.129 55.884 76.872 Example 54 629 4.013 1.552 2.412 68.947 82.914 604 0.233 0.043 0.088 53.177 75.626 Example 55 623 3.310 1.839 1.651 65.996 81.297 599 0.143 0.061 0.043 48.917 72.834 Example 56 684 26.390 10.936 22.873 83.730 87.356 650 8.502 1.664 6.470 77.063 83.549 Example 57 691 25.700 10.959 24.455 85.107 87.547 656 8.082 1.659 7.351 79.489 83.898 Example 58 697 26.282 11.455 26.383 86.102 87.378 663 8.435 1.801 8.497 81.274 83.589 Example 59 655 11.415 3.320 8.830 78.928 87.232 627 1.717 0.176 1.051 68.837 83.322 Example 60 650 11.996 3.707 7.984 77.691 87.147 623 1.887 0.215 0.867 66.792 83.167 Comp. Ex. X 702 27.042 11.822 27.977 85.646 83.945 668 8.907 1.910 9.504 80.453 77.430 Comp. Ex. A 651 8.277 3.230 6.560 78.045 83.036 624 0.929 0.162 0.596 67.374 75.838 Comp. Ex. B 638 4.609 2.656 3.165 73.041 81.723 611 0.304 0.114 0.148 59.369 73.566 Comp. Ex. C 658 10.745 2.941 9.189 80.140 86.853 630 1.529 0.143 1.134 70.868 82.633 Comp. Ex. D 633 28.002 9.056 8.961 68.186 86.034 603 10.180 1.289 1.081 52.078 81.152 Example 61 664.089 18.966 5.650 13.833 79.818 87.687 632.89 4.544 0.530 2.504 70.618 84.504 Example 62 666.119 22.795 7.758 15.647 79.897 88.114 633.85 6.455 0.911 3.147 70.753 85.292 Example 63 664.102 17.594 5.392 13.794 79.676 87.650 632.74 3.937 0.468 2.474 70.379 84.435 Example 64 649.438 13.229 3.396 8.227 76.193 86.736 620.60 2.284 0.191 0.922 64.622 82.762 Example 65 649.115 15.695 3.671 9.129 75.588 84.128 619.58 3.166 0.269 1.125 63.546 78.077 Example 66 652.109 16.642 4.559 9.955 76.583 86.040 622.36 3.540 0.366 1.327 85.255 81.500

TABLE 7 Example Comparative Transmittance@Sheet thickness 0.23 mm Transmittance@Sheet thickness 0.25 mm DSC Example λ T50 T1200 T600 T400 λ T50 T1200 T600 T400 Tg Tm Weathering No (nm) (%) (%) (%) (nm) (%) (%) (%) (° C.) (° C.) resistance Example 1 632 0.680 71.029 83.995 629 0.444 69.465 83.353 308 790 B Example 2 628 0.695 69.850 84.889 625 0.455 68.214 84.318 314 812 B Example 3 627 0.584 69.119 84.243 624 0.376 67.438 83.620 316 806 B Example 4 623 0.654 67.223 83.600 620 0.425 65.429 82.927 318 817 B Example 5 624 0.581 67.386 83.453 621 0.374 65.602 82.768 327 812 B Example 6 617 0.437 62.702 80.145 614 0.274 60.661 79.208 327 816 A Example 7 619 0.527 64.819 82.164 616 0.336 62.890 81.380 325 823 A Example 8 610 0.552 58.578 79.254 608 0.354 56.337 78.252 357 828 B Example 9 613 0.581 60.555 80.311 610 0.374 58.406 79.387 342 821 B Example 10 612 0.528 59.915 79.807 609 0.337 57.736 78.846 352 825 B Example 11 608 0.488 56.959 78.582 605 0.309 54.646 77.531 364 842 B Example 12 615 0.550 62.463 80.430 612 0.352 60.409 79.515 341 809 B Example 13 612 0.428 59.929 79.441 609 0.269 57.750 78.452 329 818 B Example 14 613 0.429 60.552 79.316 610 0.269 58.403 78.318 334 816 B Example 15 615 0.546 61.865 80.344 612 0.350 59.782 79.423 334 822 B Example 16 615 0.534 61.809 79.526 612 0.342 59.722 78.544 328 817 B Example 17 615 0.463 61.975 79.925 612 0.292 59.897 78.972 332 815 A Example 18 614 0.533 61.221 79.507 611 0.341 59.105 78.524 333 817 A Example 19 615 0.567 61.623 79.217 612 0.364 59.527 78.212 335 816 A Example 20 614 0.484 61.356 79.199 611 0.306 59.247 78.193 334 823 A Example 21 615 0.512 62.420 80.303 613 0.326 60.364 79.378 342 814 A Example 22 616 0.480 62.827 80.145 613 0.304 60.792 79.209 333 822 A Example 23 623 0.977 67.242 83.660 620 0.658 65.449 82.991 B Example 24 615 0.510 61.895 80.113 612 0.325 59.812 79.174 342 817 A Example 25 631 2.098 71.214 84.469 628 1.511 69.663 83.864 343 756 A Example 26 632 2.067 71.655 84.908 628 1.487 70.131 84.338 341 768 A Example 27 634 2.548 72.530 85.718 631 1.866 71.063 85.213 316 751 B Example 28 631 2.013 71.073 84.941 628 1.444 69.512 84.374 316 757 B Example 29 626 1.149 68.912 81.971 623 0.785 67.218 81.172 B Example 30 625 1.122 68.151 82.706 622 0.765 66.412 81.963 B Example 31 616 0.912 62.865 78.790 613 0.611 60.832 77.754 352 856 B Example 32 617 0.907 63.414 76.237 614 0.607 61.409 75.019 361 794 B Example 33 623 0.871 66.874 78.888 620 0.581 65.060 77.859 355 789 A Example 34 609 0.278 57.150 63.659 606 0.168 54.845 61.667 373 840 B Example 35 623 1.070 67.047 83.255 620 0.727 65.243 82.555 B Example 36 610 0.406 58.622 78.390 607 0.253 56.383 77.325 344 823 B Example 37 610 0.461 58.642 77.745 607 0.291 56.404 76.633 341 828 B Example 38 605 0.677 54.138 62.685 602 0.442 51.711 60.643 408 820 S Example 39 603 0.150 52.457 55.748 600 0.086 49.968 53.384 383 839 B Example 40 608 0.431 56.733 75.213 605 0.270 54.411 73.925 356 819 B Example 41 604 0.366 53.525 71.106 601 0.226 51.075 69.547 364 818 B Example 42 617 2.103 62.924 72.936 614 1.514 60.894 71.498 401 798 S Example 43 633 6.037 71.324 81.639 630 4.765 69.779 80.815 393 835 S Example 44 618 0.482 63.505 77.123 615 0.305 61.506 75.967 348 752 A Example 45 629 5.545 69.384 83.643 625 4.345 67.719 82.973 393 824 S Example 46 601 0.293 51.122 66.591 598 0.178 48.587 64.761 367 807 B Example 47 619 5.117 63.589 75.578 616 3.981 61.594 74.316 S Example 48 611 4.002 58.474 81.614 608 3.048 56.228 59.517 392 794 S Example 49 609 4.131 57.239 72.049 606 3.155 54.938 70.550 391 803 S Example 50 625 0.410 67.667 77.422 622 0.256 65.899 76.288 332 704 B Example 51 625 8.746 66.632 78.095 621 7.130 64.804 77.009 B Example 52 619 9.232 63.656 72.094 616 7.561 61.665 70.599 370 785 B Example 53 604 0.217 53.307 75.588 601 0.128 50.849 74.326 359 848 B Example 54 601 0.132 50.486 74.247 598 0.075 47.930 72.894 360 860 B Example 55 596 0.078 46.073 71.251 593 0.042 43.395 69.701 377 873 B Example 56 645 6.778 75.794 82.808 641 5.404 74.545 82.073 348 752 S Example 57 652 6.412 78.411 83.187 648 5.088 77.348 82.481 326 833 B Example 58 659 6.720 80.341 82.851 655 5.354 79.419 82.120 307 656 B Example 59 623 1.175 66.979 82.561 620 0.805 65.172 81.808 C Example 60 619 1.304 64.803 82.393 616 0.901 62.873 81.626 324 796 D Comp. Ex. X 664 7.133 79.453 76.190 660 5.712 78.466 74.969 273 690 E Comp. Ex. A 620 0.600 65.422 74.475 617 0.387 63.526 73.137 E Comp. Ex. B 608 0.176 56.958 72.035 605 0.102 54.645 70.536 E Comp. Ex. C 627 1.036 69.147 83.813 624 0.701 67.467 81.002 319 751 E Comp. Ex. D 599 8.257 49.343 80.209 596 6.697 46.753 79.278 374 733 S Example 61 629 3.416 68.940 83.897 625 2.565 67.237 83.261 435 S Example 62 630 5.013 69.031 84.727 628 3.892 67.333 84.156 440 S Example 63 629 2.918 68.652 83.806 625 2.161 66.931 83.162 420 S Example 64 617 1.608 62.531 81.992 614 1.131 60.471 81.208 440 S Example 65 616 2.299 61.508 76.927 613 1.668 59.396 75.770 450 S Example 66 619 2.600 63.233 80.640 615 1.906 61.209 79.753 456 S

From the results shown in the tables above, it can be confirmed that the glasses of Examples 1 to 66 exhibited high transmittance of light in the visible region (the violet region to the red region), achieved excellent near-infrared cutting performance, and suppressed a reduction in weathering resistance.

With regard to weathering resistance, it can be confirmed from a comparison between Examples 1 to 58 and Example 59 that, relative to Example 59, in which the value calculated as “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” was 0, Examples 1 to 58, in which this value was higher, exhibited better weathering resistance.

In a comparison between Example 59 and Example 60, Example 60, in which the value calculated as “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” was 0 and the value of “(Na₂O+K₂O+ZnO)/Li₂O” was more than 1.4, which was higher than in Example 59, had a higher degree of deliquescence than Example 59, and had relatively poor weathering resistance.

In Comparative Example X, the value calculated as “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” was more than 0, but the value of “(Na₂O+K₂O+ZnO)/Li₂O” was high, more than 11, and weathering resistance was low.

Comparative Example A, Comparative Example B and Comparative Example C are glasses comprising only three components, namely, P₂O₅, Li₂O and CuO, and exhibit extremely low weathering resistance.

In Comparative Example D, the O/P ratio was more than 3.2, and the prescribed transmittance characteristics could not be achieved.

Among Examples in which the evaluation classification was S or A for the evaluation of weathering resistance by eye described above, haze values were determined for Examples 25, 33, 56 and 61 to 66 using a haze meter. Determined haze values are shown in Table 8.

TABLE 8 Weathering resistance (3 × Al₂O₃+ Y₂O₃ + La₂O₃ + (evaluated Gd₂O₃ + BaO/3 + (CaO + SrO)/6) (MgO + CaO + SrO + BaO + ZnO)/ by eye) Haze value O/P ratio (mol %) (Li₂O + Na₂O + K₂O) Example25 A 43.2% 2.93 8.55 0.73 Example33 A 34.9% 2.93 4.52 1.47 Example56 S 0.0% 3.01 12.93 0.22 Example61 S 13.0% 3.00 14.53 26.38 Example62 S 8.0% 3.02 14.93 26.64 Example63 S 1.0% 3.00 16.37 5.72 Example64 S 10.0% 3.02 13.42 21.45 Example65 S 0.5% 3.06 18.03 22.36 Example66 S 0.4% 3.04 15.11 23.00

As shown in Table 8, Examples 56 and 61 to 66, for which the evaluation classification was S for the evaluation of weathering resistance by eye, had haze values of 15% or less, which were lower in than Examples 25 and 33, for which the evaluation classification was A for the evaluation of weathering resistance by eye.

From the results above, it can be confirmed that in order to achieve both improved transmittance of light in the visible region and improved near-infrared cutting performance as well as achieve a haze value of 15% or less, the O/P ratio preferably falls within the range 3.00 to 3.15 and the value calculated as “(3×Al₂O₃+Y₂O₃+La₂O₃+Gd₂O₃+BaO/3+(CaO+SrO)/6)” (units: mol %) preferably falls within the range 10.0% to 40.0%.

Finally, the aspects described above will be summarized.

Glasses 1 to 6, which are described in detail above, are provided by one aspect.

In one embodiment, Glasses 1 to 6 can have an Al₂O₃ content of less than 2.0 mol %.

In one embodiment, Glasses 1 to 6 can have a total content of Al₂O₃, La₂O₃, Y₂O₃ and Gd₂O₃ (Al₂O₃+La₂O₃+Y₂O₃+Gd₂O₃) of 0.1 mol % or more.

In one embodiment, Glasses 1 to 6 can have the following transmittance characteristics.

A glass for which the half value Δ_(T)50, which is the wavelength at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm has a thickness of 0.25 mm or less, and

-   -   at this thickness, the external transmittance T600 including         reflection losses at a wavelength of 600 nm is 50% or more, and         the external transmittance T1200 including reflection losses at         a wavelength of 1200 nm is 30% or less.

A glass for which the half value Δ_(T)50, which is the wavelength at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm has a thickness of 0.25 mm or less, and

-   -   at this thickness, the external transmittance T600 including         reflection losses at a wavelength of 600 nm is 50% or more, and         the external transmittance T1200 including reflection losses at         a wavelength of 1200 nm is β1% or less,     -   β1 is a value calculated from Equation B1 below:

β1=64×R−170  (Equation B1)

In equation B1 above,

-   -   R is the ratio (O ion/P ion).

As transmittance characteristics calculated at a thickness of 0.11 mm, the half value Δ_(T)50, which is the wavelength at which the external transmittance including reflection losses becomes 50%, falls within the range 600 nm to 650 nm, the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 30% or less, and the external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.

As transmittance characteristics calculated at a thickness of 0.21 mm, the half value Δ_(T)50, which is the wavelength at which the external transmittance including reflection losses becomes 50%, falls within the range 600 nm to 650 nm, the external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 25% or less, and the external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.

A glass for which the half value Δ_(T)50, which is the wavelength at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm has a thickness of 0.25 mm or less, and

-   -   at this thickness, the external transmittance T600 including         reflection losses at a wavelength of 600 nm is 50% or more, and         the external transmittance T1200 including reflection losses at         a wavelength of 1200 nm is 30% or less.

A glass for which the half value Δ_(T)50, which is the wavelength at which the external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm has a thickness of 0.25 mm or less, and

-   -   at this thickness, the external transmittance T600 including         reflection losses at a wavelength of 600 nm is 50% or more, and         the external transmittance T1200 including reflection losses at         a wavelength of 1200 nm is β1% or less, β1 is a value calculated         from equation B1 below:

β1=64×R−170  (Equation B1)

In equation B1 above,

-   -   R is the ratio (O ion/P ion).

Provided by one aspect is a near-infrared cut filter comprised of the above near-infrared absorbing glass.

The embodiments disclosed here are exemplifications in every sense and should not be considered to be limiting examples. The scope of the present invention is indicated by the claims, not by the explanations given above, and it is intended to cover all alternative forms falling within the spirit and scope of the invention.

For example, by subjecting the glass compositions exemplified above to compositional adjustments explained in the description, it is possible to obtain a near-infrared absorbing glass according to one aspect of the present invention.

In addition, it is of course possible to arbitrarily combine two or more matters that are described in the description as examples or preferred ranges. 

1. A near-infrared absorbing glass, which comprises at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, and Y ions, comprises P ions, Li ions, and Cu ions as essential cations, and comprises at least O ions as anions, wherein a ratio of a content of O ions relative to a content of P ions (O ion/P ion) is 3.15 or less; in a glass composition indicated by anion %, a content of O ions is 90.0 anion % or more; and in an oxide-based glass composition on a molar basis, a total content of oxides of the main cations is 90.0% or more, a total content of MgO and Al₂O₃(MgO+Al₂O₃) is 8.0% or less, a ratio of a total content of Na₂O, K₂O, and ZnO relative to a content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less, a total content of B₂O₃ and SiO₂ (B₂O₃+SiO₂) is 3.0% or less, and a content of CuO is α₁% or more, where α₁ is a value calculated by Equation 1 below, α₁=70400×exp(−2.855×R)  (Equation 1) and in Equation 1 above, R is the ratio (O ion/P ion).
 2. A near-infrared absorbing glass, which comprises at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, and Y ions, comprises P ions, Li ions, and Cu ions as essential cations, and comprises at least O ions as anions, wherein a ratio of a content of O ions relative to a content of P (O ion/P ion) ions is 3.15 or less; in a glass composition indicated by anion %, a content of O ions is 90.0 anion % or more; and in an oxide-based glass composition on a molar basis, a total content of oxides of the main cations is 90.0% or more, a total content of MgO and Al₂O₃(MgO+Al₂O₃) is 8.0% or less, a ratio of a total content of Na₂O, K₂O, and ZnO relative to a content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less, a total content of B₂O₃ and SiO₂ (B₂O₃+SiO₂) is 3.0% or less, and which satisfies Equation 2 below: C−3200×exp(−2.278×R)≥0  (Equation 2) and in Equation 2 above, C is a content of CuO (units: mmol/cc) per molar volume of the glass, and R is the ratio (O ion/P ion).
 3. A near-infrared absorbing glass, which comprises at least four kinds of main cations selected from the group consisting of P ions, Li ions, Cu ions, Al ions, Ba ions, Sr ions, Ca ions, Mg ions, Zn ions, K ions, Na ions, La ions, Gd ions, Y ions, B ions and Si ions, comprises P ions, Li ions, and Cu ions as essential cations, and comprises at least O ions as anions, wherein a ratio of a content of O ions relative to a content of P ions (O ion/P ion) is 3.15 or less; in a glass composition indicated by anion %, a content of O ions is 90.0 anion % or more; and in an oxide-based glass composition on a molar basis, a total content of oxides of the main cations is 90.0% or more, a total content of MgO and Al₂O₃(MgO+Al₂O₃) is 8.0% or less, a ratio of a total content of Na₂O, K₂O, and ZnO relative to a content of Li₂O ((Na₂O+K₂O+ZnO)/Li₂O) is 2.4 or less, A₁, which is calculated by Equation 3 below, is 2500 or more, A ₁={O(P)−O(others)}×Cu  (Equation 3) and in Equation 3 above, O(P) denotes an amount of oxygen that constitutes an oxide of P ions in the oxide-based glass composition, O(others) denotes an amount of oxygen determined by subtracting the value of O(P) from an amount of oxygen that constitutes oxides of the main cations in the oxide-based glass composition, and Cu denotes a content of CuO on a molar basis in the oxide-based glass composition. 4-6. (canceled)
 7. The near-infrared absorbing glass according to claim 1, wherein a total content of Na₂O and K₂O is less than 15.0 mol %.
 8. The near-infrared absorbing glass according to claim 1, wherein a content of Al₂O₃ is less than 2.0 mol %.
 9. The near-infrared absorbing glass according to claim 1, wherein a total content of Al₂O₃, La₂O₃, Y₂O₃ and Gd₂O₃ (Al₂O₃+La₂O₃+Y₂O₃+Gd₂O₃) is 0.1 mol % or more.
 10. The near-infrared absorbing glass according to claim 1, wherein a glass for which a half value λ_(T)50, which is a wavelength at which an external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm has a thickness of 0.25 mm or less, and at the thickness, an external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and an external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 30% or less.
 11. The near-infrared absorbing glass according to claim 1, wherein a glass for which a half value λ_(T)50, which is a wavelength at which an external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 633 nm has a thickness of 0.25 mm or less, and at the thickness, an external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and an external transmittance T1200 including reflection losses at a wavelength of 1200 nm is β1% or less, β1 is a value calculated from Equation B1 below: β1=64×R−170  (Equation B1) and in equation B1 above, R is the ratio (O ion/P ion).
 12. The near-infrared absorbing glass according to claim 1, wherein as transmittance characteristics calculated at a thickness of 0.11 mm, a half value λ_(T)50, which is a wavelength at which an external transmittance including reflection losses becomes 50%, falls within a range 600 nm to 650 nm, an external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 30% or less, and an external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.
 13. The near-infrared absorbing glass according to claim 1, wherein as transmittance characteristics calculated at a thickness of 0.21 mm, a half value λ_(T)50, which is a wavelength at which an external transmittance including reflection losses becomes 50%, falls within a range 600 nm to 650 nm, an external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 25% or less, and an external transmittance T400 including reflection losses at a wavelength of 400 nm is 70% or more.
 14. The near-infrared absorbing glass according to claim 1, wherein a glass for which a half value λ_(T)50, which is a wavelength at which an external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm has a thickness of 0.25 mm or less, and at the thickness, an external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and an external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 30% or less.
 15. The near-infrared absorbing glass according to claim 1, wherein a glass for which a half value λ_(T)50, which is a wavelength at which an external transmittance including reflection losses becomes 50% at a wavelength of 550 nm or longer, is 645 nm has a thickness of 0.25 mm or less, and at the thickness, an external transmittance T600 including reflection losses at a wavelength of 600 nm is 50% or more, and an external transmittance T1200 including reflection losses at a wavelength of 1200 nm is 01% or less, β₁ is a value calculated from equation B1 below: β1=64×R−170  (Equation B1) and in equation B1 above, R is the ratio (O ion/P ion).
 16. A near-infrared cut filter, which is comprised of the near-infrared absorbing glass according to claim
 1. 17. A near-infrared cut filter, which is comprised of the near-infrared absorbing glass according to claim
 2. 18. A near-infrared cut filter, which is comprised of the near-infrared absorbing glass according to claim
 3. 